GetAsync() only takes one parameter.

You also didnt define player in the autosave loop so that would error your code, stopping it from running.

I rewrote the code a bit, adding a function to Save the player's data, load the player's data, and create the leaderstat items

Troubleshooting:

It worked when I tested it BUT if you have any issues with saving, try these troubleshooting:

1) Go to Studio -> Home tab -> Game settings (it's a blue gear) -> Options -> and turn on all three options.

2) Sometimes studio is wonky not saving datastores, so try playing in game and see what happens.

3) Another thing to look out for, make sure you're changing the values inside the objects on the server If you change them in the properties in play mode or in a local script, they won't change. only if you change them in a server script or [click this button to go into server mode (https://imgur.com/a/pSjaUYT)

If neither of those work, we can take a look at your game thru team create and see why it isnt working.

Code:

local dataStore = game:GetService("DataStoreService"):GetDataStore("Test4")

function createValueObjects(player)
    local leaderstatsFolder = Instance.new("Folder")
    leaderstatsFolder.Name = "leaderstats"
    leaderstatsFolder.Parent = player

    local kills = Instance.new("IntValue")
    kills.Name = "Eliminations"
    kills.Value = 0
    kills.Parent = leaderstatsFolder

    local deaths = Instance.new("IntValue")
    deaths.Name = "Deaths"
    deaths.Value = 0
    deaths.Parent = leaderstatsFolder

    local careerKills = Instance.new("IntValue")
    careerKills.Name = "Career Eliminations"
    careerKills.Parent = leaderstatsFolder

    local careerDeaths = Instance.new("IntValue")
    careerDeaths.Name = "Career Deaths"
    careerDeaths.Parent = leaderstatsFolder

    local careerWins = Instance.new("IntValue")
    careerWins.Name = "Career Wins"
    careerWins.Parent = leaderstatsFolder

    local careerLosses = Instance.new("IntValue")
    careerLosses.Name = "Career Losses"
    careerLosses.Parent = leaderstatsFolder

    local credits = Instance.new("IntValue")
    credits.Name = "Credits"
    credits.Parent = leaderstatsFolder

    return careerKills, careerDeaths, careerWins, careerLosses, credits
end

function saveData(player)
    local careerKills =  player.leaderstats["Career Eliminations"]
    local careerDeaths =  player.leaderstats["Career Deaths"]
    local careerWins =  player.leaderstats["Career Wins"]
    local careerLosses =  player.leaderstats["Career Losses"]
    local credits =  player.leaderstats["Credits"]

    print("values to save", careerKills.Value,careerDeaths.Value,careerWins.Value,careerLosses.Value,credits.Value)

    local saves = {careerKills.Value,careerDeaths.Value,careerWins.Value,careerLosses.Value,credits.Value}

    local success, err = pcall(function()
        dataStore:SetAsync("SAVE-"..player.UserId,saves)
        print("Saved data for "..player.Name)
    end)

    if not success then error(err) end  
end

function getData(player)
    local dataFromDatastore 

    local success, err = pcall(function()
        dataFromDatastore = dataStore:GetAsync("SAVE-"..player.UserId)
    end)

    if not success then error(err) end  
    return dataFromDatastore
end

game.Players.PlayerAdded:Connect(function(player)
    local careerKills, careerDeaths, careerWins, careerLosses, credits = createValueObjects(player)
    local dataFromDatastore = getData(player)


    if not dataFromDatastore then
        careerWins.Value = 0
        careerLosses.Value = 0
        careerKills.Value = 0
        careerDeaths.Value = 0
        credits.Value = 500
        print("New Player joined the game")
    else
        careerKills.Value = dataFromDatastore[1]
        careerDeaths.Value = dataFromDatastore[2]
        careerWins.Value = dataFromDatastore[3]
        careerLosses.Value = dataFromDatastore[4]
        credits.Value = dataFromDatastore[5]
        print("Data Loaded")
    end
end)

game.Players.PlayerRemoving:Connect(function(player)
    saveData(player)
end)

game:BindToClose(function()
    if game:GetService("RunService"):IsStudio() then return end

    for _,player in pairs(game.Players:GetPlayers()) do
        saveData(player)
    end
end)

--ADDS ONE TO TO THE PLAYERS CARRER ELIMINATIONS EVERY SECOND.
--THIS IS JUST FOR TESTING THAT THE DATASTORE WORKS
--DELETE AFTER YOU'RE DONE TESTING
spawn(function()
    while true do
        wait(1)
        for _, player in pairs(game.Players:GetPlayers())do
            player.leaderstats["Career Eliminations"].Value = player.leaderstats["Career Eliminations"].Value + 1
        end
    end 
end)

--AUTOSAVES EVERYONE'S DATA
while true do
    for _,player in pairs(game.Players:GetPlayers()) do
        saveData(player)
    end
    wait(60)
end

PS, only 4 of your values in the leaderstats will load. The values will be in the leaderstats and this script will work, but only four will show up on the leaderboard as you can see here. The solution to this would be to either use a custom leaderboard / use guis instead or don't display so many stats.