I have a MGN account, and when I log in through the game, it tells me I need to add the game to a list on my account. So I go to my account on the site, hit manage games, and there it tells me I have no games added to my library and no means of changing that. What gives?

We're rolling out access to online over time. You'll get an email when your account has been activated.

Also, please read the big red text at the top of the screen. Next time, check the SSF2 section instead (there are lots of posts about this in there already).