I'm trying to create a fivem lua volleyball based on this video…

This is a basic outline and a starting point for creating a FiveM Lua volleyball game mode based on the video you provided. Please note that this is a rough code outline and may require adjustments and improvements to work correctly in your specific server environment.

1. First, create a new folder in your FiveM resources folder and name it "volleyball".

2. Inside the "volleyball" folder, create a "__resource.lua" file and add the following code:

resource_manifest_version '44febabe-d386-4d18-afbe-5e627f4af937'
client_script 'client.lua'
server_script 'server.lua'

3. Now, create a "client.lua" file inside the "volleyball" folder and add the following code:

local playingVolleyball = false
local volleyballCourt = vector3(-2996.74, 137.225, 16.5668)

Citizen.CreateThread(function()
    while true do
        Citizen.Wait(0)

        local playerPed = PlayerPedId()
        local playerCoords = GetEntityCoords(playerPed)

        if GetDistanceBetweenCoords(playerCoords, volleyballCourt, true) < 20.0 and not playingVolleyball then
            ShowHelpNotification('Press ~INPUT_CONTEXT~ to play volleyball.')

            if IsControlJustPressed(0, 51) then -- 51 is the E key (INPUT_CONTEXT)
                playingVolleyball = true
                TriggerServerEvent('volleyball:join')
            end
        end
    end
end)

RegisterNetEvent('volleyball:startGame')
AddEventHandler('volleyball:startGame', function()
    -- Insert the code for starting the volleyball game here (e.g., creating the ball, setting up players...)
end)

function ShowHelpNotification(text)
    BeginTextCommandDisplayHelp('STRING')
    AddTextComponentSubstringPlayerName(text)
    EndTextCommandDisplayHelp(0, false, true, -1)
end

4. Create a "server.lua" file inside the "volleyball" folder and add the following code:

local playersInVolleyball = {}

RegisterNetEvent('volleyball:join')
AddEventHandler('volleyball:join', function()
    local source = source
    local playerCount = #playersInVolleyball

    if playerCount >= 2 then
        TriggerClientEvent('esx:showNotification', source, 'The volleyball game is full!')
    else
        table.insert(playersInVolleyball, source)
        TriggerClientEvent('esx:showNotification', source, 'You have joined the volleyball game!')

        if playerCount == 1 then
            StartVolleyballGame()
        end
    end
end)

function StartVolleyballGame()
    for _, player in ipairs(playersInVolleyball) do
        TriggerClientEvent('volleyball:startGame', player)
    end

    SetTimeout(300000, function() -- 5 minutes (300000) game time
        EndVolleyballGame()
    end)
end

function EndVolleyballGame()
    -- Insert the code for ending the volleyball game and determining the winner
    playersInVolleyball = {}
end

With the basic structure set, you will need to fill in the details, such as creating the ball, synchronizing its position, handling hits, and determining the winner. You might also want to consider implementing a user interface for the players' scores and any other relevant information.

Creating the ball and synchronizing its position requires to create a shared object which can be accessed by all clients. Moreover, you need to create a function to handle player's hits on the ball. Here's an example of how to do this:

1. Modify your "client.lua" file to add the ball creation and position synchronization:

-- Add this code to the beginning of the file
local ball = nil
local ballCoords = vector3(0, 0, 0)

-- Modify the 'volleyball:startGame' event to add ball creation 
RegisterNetEvent('volleyball:startGame')
AddEventHandler('volleyball:startGame', function(serverBallCoords)
    if ball ~= nil then
        DeleteEntity(ball)
    end

    ballCoords = serverBallCoords
    local model = "prop_vball_01"
    RequestModel(model)

    while not HasModelLoaded(model) do
        Wait(0)
    end

    ball = CreateObject(GetHashKey(model), ballCoords.x, ballCoords.y, ballCoords.z, false, true, false)
    SetEntityCollision(ball, true)

    Citizen.CreateThread(function()
        while ball ~= nil do
            Wait(200) -- Update the ball's position every 200 ms
            ballCoords = GetEntityCoords(ball)
            TriggerServerEvent('volleyball:updateBallPosition', ballCoords)
        end
    end)
end)

RegisterNetEvent('volleyball:updateBallPosition')
AddEventHandler('volleyball:updateBallPosition', function(serverBallCoords)
    ballCoords = serverBallCoords
    SetEntityCoords(ball, ballCoords.x, ballCoords.y, ballCoords.z)
end)

2. Modify your "server.lua" file to add the ball position synchronization between clients:

local ballCoords = vector3(-2996.74, 137.225, 25.5668)

RegisterNetEvent('volleyball:updateBallPosition')
AddEventHandler('volleyball:updateBallPosition', function(clientBallCoords)
    ballCoords = clientBallCoords
    for _, player in ipairs(playersInVolleyball) do
        TriggerClientEvent('volleyball:updateBallPosition', player, ballCoords)
    end
end)

-- Modify the 'StartVolleyballGame' function to pass the initial ball position to clients
function StartVolleyballGame()
    for _, player in ipairs(playersInVolleyball) do
        TriggerClientEvent('volleyball:startGame', player, ballCoords)
    end
    SetTimeout(300000, function()
        EndVolleyballGame()
    end)
end

3. Add a function in "client.lua" to detect and handle players hitting the ball:

Citizen.CreateThread(function()
    while true do
        Citizen.Wait(0)

        if ball ~= nil and playingVolleyball then
            local playerPed = PlayerPedId()
            local playerCoords = GetEntityCoords(playerPed)
            
            SetEntityHasGravity(ball, true) 

            if GetDistanceBetweenCoords(playerCoords, ballCoords, true) < 1.0 then
                    
                local ballDirection = vector3(
                    ballCoords.x - playerCoords.x,
                    ballCoords.y - playerCoords.y,
                    ballCoords.z - playerCoords.z
                )

                local hitPower = 10.0 -- You can adjust this value to change how hard the ball is hit
                ApplyForceToEntity(
                    ball,
                    1,
                    ballDirection.x * hitPower,
                    ballDirection.y * hitPower,
                    ballDirection.z * hitPower,
                    0, 0, 0,
                    0, false, true, true, true, true
                )
            end
        end
    end
end)

With these changes, you should now have a ball that is created, and its position is synchronized between clients. Furthermore, there is a function that detects when players hit the ball and applies force to it. Remember to adjust the hitPower value for your desired gameplay experience.