What's wrong with my leveling system?

I seem to be having a problem in making a leveling system in my game which consists of 3 values, Level, Exp and MaxExp. But the problem is, it doesnt seem to be working and also doesnt save and gives me an error:

"19:21:19.295 - 502: API Services rejected request with error. HTTP 403 (Forbidden)"

and doesnt changeal l of the 3 values given and stays 0. And since the MaxExp is also 0, when I use the exp giver it instantly gets me to level 2 and then works normally after that. If you guys have any fixes or have a better leveling system then please let me know. (This is in teamcreate, but I am the owner of the game)

----Variables----
local Players = game:GetService("Players")
local ServerStorage = game:GetService("ServerStorage")
local DataStoreService = game:GetService("DataStoreService")

local StoredLevel = DataStoreService:GetDataStore("Level")
local StoredExp = DataStoreService:GetDataStore("Exp")
local StoredMaxExp = DataStoreService:GetDataStore("MaxExp")

----Code----
Players.PlayerAdded:Connect(function(player)
	
	local Folder = Instance.new("Folder") --creates a new folder in the player
	Folder.Name = "Stats"
	Folder.Parent = player
	
	local Level = Instance.new("IntValue") --creates a value in the folder
	Level.Name = "Level"
	Level.Parent = player:WaitForChild("Stats")
	
	local Exp = Instance.new("IntValue") --creates another value in the folder
	Exp.Name = "Exp"
	Exp.Parent = player:WaitForChild("Stats")
	
	local MaxExp = Instance.new("IntValue")
	MaxExp.Name = "MaxExp"
	MaxExp.Parent = player:WaitForChild("Stats") --creates another value in the folder
	
	local LevelData
	local ExpData
	local MaxExpData
	--variables to be used later

	local success, errormessage = pcall(function()
		LevelData = StoredLevel:GetAsync(player.UserId)
		ExpData = StoredExp:GetAsync(player.UserId)
		MaxExpData = StoredMaxExp:GetAsync(player.UserId)
		-- setting the variables
	end)
	
	if success then
		Level.Value = LevelData or 1 --if you dont have a datastore, you get your level to 1
		Exp.Value = ExpData
	 	MaxExp.Value = MaxExp.Data or 11 --same here 			 
              
	else
		print("There Was an Error When Getting Data")
		warn(errormessage)
	end
	
	ServerStorage.GiveExp.Event:Connect(function(amount, plr) --bindable event to give exp
		if player.Name == plr.Name then
			Exp.Value = Exp.Value + amount
		end
	end)
	
	Exp.Changed:Connect(function()
		if Exp.Value >= MaxExp.Value then
			
			local LeftoverExp = MaxExp.Value - Exp.Value
			Exp.Value = 0
			Level.Value = Level.Value + 1
			MaxExp.Value =  10 + Level.Value^3 --this is the level formula
			Exp.Value = Exp.Value - LeftoverExp

		end
	end)
end)


Players.PlayerRemoving:Connect(function(player) -- saves data when player leaves
	
	local success, errormessage = pcall(function()
		StoredLevel:UpdateAsync(player.UserId, player.Stats.Level.Value)
		StoredExp:UpdateAsync(player.UserId, player.Stats.Exp.Value)
		StoredMaxExp:UpdateAsync(player.UserId, player.Stats.MaxExp.Value)
	end)
	
	if success then
		print("Player Data Successfully Saved!")
	else
		print("There Was an Error When Saving Data.")
		warn(errormessage)
	end
	
end)

And this is the exp giver remote event

----Variables----
local ServerStorage = game:GetService("ServerStorage")
local CanGive = true

script.Parent.Touched:Connect(function(hit) -- touched function to give player 5 exp
	if hit.Parent then
		local player = game.Players:GetPlayerFromCharacter(hit.Parent)
		if player then
			if CanGive == true then
				CanGive = false
				ServerStorage.GiveExp:Fire(5, player)
				wait(1)
				CanGive = true
			end
		end
	end
end)