This datastore that saves a table doesn't work, can someone help me please?

It's because you got the table from the datastore, but you still need to set the values to the values of the table. Fixed script:

local purchasedfolder = game.Workspace.PurchasedValues
local HttpService = game:GetService("HttpService")
local DataStoreService = game:GetService("DataStoreService")
local DataStore = DataStoreService:GetDataStore("TableTestDataStore")
game.Players.PlayerAdded:Connect(function(player)
	local key = player.Name.."-"..player.UserId
	local encodedData = DataStore:GetAsync(key)
	local data = HttpService:JSONDecode(encodedData)
	-- Set the values from the decoding
	purchasedfolder.Purchasedbmw.Value = data[1]
	purchasedfolder.Purchasedgtr.Value = data[2]
	purchasedfolder.Purchasedhoon.Value = data[3]
	purchasedfolder.Purchasedmc.Value = data[4]
	purchasedfolder.Purchasedpor.Value = data[5]
	purchasedfolder.Purchaseds13.Value = data[6]
end)
game.Players.PlayerRemoving:Connect(function(player)
	local data  = {
    	purchasedfolder.Purchasedbmw.Value,
	    purchasedfolder.Purchasedgtr.Value, 
	    purchasedfolder.Purchasedhoon.Value,
	    purchasedfolder.Purchasedmc.Value,
	    purchasedfolder.Purchasedpor.Value,
	    purchasedfolder.Purchaseds13.Value
	}
	local key = player.Name.."-"..player.UserId
	local normalData = HttpService:JSONEncode(data)
	DataStore:SetAsync(key,normalData)
end)

I hope this fixed your problem!