I'm hoping I don't get banned for this, but so everyone knows:
You have to download the ISO, and install a crack/update to play the game, due to something not allowing the key to be entered in the installer, only in the game. The key works online, and you can play with the DLC if you buy it. It works exactly like the original game. The crack does not allow you to play the game without the key. Neither does the ISO or anything like that.