You will need to download and play the game via Origin instead of Steam. Solution: Contact EA support with a screenshot of your Steam receipt email and they will add the game to your Origin account. Problem 1: When you try to access the server browser, the have will ask you to enter a serial key, but you don't have one. You will be resolving at least two problems and possibly a third: Listen to me, you are able to play multiplayer with this version but you will need to do a little work.
