How am I able to make a gamepass give in-game cash?

Iv'e been looking at a few scripts and each one I try says GamePassService and I have heard that it GamePassService does not work anymore so what I am I able to do?

*Script Location: ServerScriptService

Script Information: This handles purchases (note, you can only have one script handling purchases per game)*

local MarketplaceService = game:GetService("MarketplaceService")
local gamepassid = 0

function getPlayerFromId(id)
	for i,v in pairs(game.Players:GetChildren()) do
		if v.userId == id then
			return v
		end
	end
	return nil
end
 
MarketplaceService.ProcessReceipt = function(receiptInfo)
	local productId = receiptInfo.ProductId
	local playerId = receiptInfo.PlayerId
	local player = getPlayerFromId(playerId)
	if productId == gamepassid then
		player.leaderstats.cash.Value = player.leaderstats.cash.Value + 300
	end
	return Enum.ProductPurchaseDecision.PurchaseGranted		
end

*Script Location: StarterGui

Script Information: This handles the purchasing when you click a button*

local plr = game.Players.LocalPlayer
local button = script.Parent
local gamepassid = 0

button.MouseButton1Down:connect(function()
	game:GetService("MarketplaceService"):PromptProductPurchase(plr, gamepassid)
end)

Hope that helped :)