[SOLVED] Unable to cast Instance to int64?

Explanation: So I was trying to make a top donator leaderboard. However, I ended up encountering an error while trying to do so. I was trying to save the info of the donation that a player made into a DataStore so that the leaderboard updates. But when I put the second argument which was supposed to be the value of the DataStore in line 43, it gives me an error saying "Unable to cast Instance to int64". This may be because I got no clue how to write the second argument and so I tried to get the PriceInRobux and make it as a value for the argument by doing:

game:GetService("MarketplaceService"):GetProductInfo(--[[Some Arguments here]]).PriceInRobux

I know I was not supposed to do that. Does anyone have any idea how to write the second argument?

Here's the ServerScript named "DeveloperProductServer" located in ServerScriptService:

local MarketPlaceService = game:GetService("MarketplaceService")
local DataStoreService = game:GetService("DataStoreService")
local RobuxDataStore = DataStoreService:GetOrderedDataStore("RobuxDateStore")
local RobuxDonateEvent = game:GetService("ReplicatedStorage"):WaitForChild("EventsFolder"):WaitForChild("RobuxDonateEvent")

local function UpdateLeaderBoard()
    local Success, ErrorMessage = pcall(function()
        local Data = RobuxDataStore:GetSortedAsync(false, 15)
        local RobuxDSPage = Data:GetCurrentPage()
        for RobuxDonated, data in ipairs(RobuxDSPage) do
            local Username = game:GetService("Players"):GetNameFromUserIdAsync(tonumber(data.key))
            local RobuxAmount = data.value
            local IsOnLeaderBoard = false
            for i, v in pairs(workspace:WaitForChild("GlobalLeaderboard"):WaitForChild("lbGUI"):WaitForChild("Holder"):GetChildren()) do
                if v.Player.Text == Username then
                    IsOnLeaderBoard = true
                    break   
                end
            end
            if RobuxAmount and IsOnLeaderBoard == false then
                local ClonelbFrame = game:GetService("ServerStorage"):WaitForChild("lbFrame"):Clone()
                ClonelbFrame.Player.Text = Username
                ClonelbFrame.Amount.Text = RobuxAmount
                ClonelbFrame.Position = UDim2.new(0, 0, ClonelbFrame.Position.Y.Scale + (0.08 * #workspace:WaitForChild("GlobalLeaderboard"):WaitForChild("lbGUI"):WaitForChild("Holder"):GetChildren()), 0)
                ClonelbFrame.Parent = workspace:WaitForChild("GlobalLeaderboard"):WaitForChild("lbGUI"):WaitForChild("Holder")
            end
        end
    end)
    if not Success then
        error(ErrorMessage)
    end
end

local function processReceipt(ReceiptInfo)
    local PlayerUserId = game:GetService("Players"):GetPlayerByUserId(ReceiptInfo.PlayerId)
    if not PlayerUserId then
        return Enum.ProductPurchaseDecision.NotProcessedYet
    end
    print("Player Donated Robux!")
    RobuxDonateEvent:FireClient(PlayerUserId)
    while true do
        for _, Player in pairs(game:GetService("Players"):GetPlayers()) do
            RobuxDataStore:SetAsync(game:GetService("Players"):GetNameFromUserIdAsync(PlayerUserId)) -- What Do I Write For The Second Argument??
        end
        for _, Frame in pairs(workspace:WaitForChild("GlobalLeaderboard"):WaitForChild("lbGUI"):WaitForChild("Holder"):GetChildren()) do
            Frame:Destroy()
        end
        UpdateLeaderBoard()
        wait(10)
    end
    return Enum.ProductPurchaseDecision.PurchaseGranted
end

MarketPlaceService.ProcessReceipt = processReceipt