I'm not sure! I used Paypal normally like I do on everything, after waiting a bit I tried to trick the system by asking for a new password to see if it would let me sign in (which it didn't, it said I still needed an account)
But yeah It only took like an hour after I bought it for the game to show up! Not horrible, was just checking on it =) not too worried since i plan on waiting for my steam key to play so that my progress saves! Just wanted to make sure it had gone through.