Better safe than sorry.
Do not follow the client based registration process.
Apparently SE created "maintenance accounts" for a lot of people. You will have 1 "account" with your characters and the others will be empty.
The client based registration process assigned my code arbitrarily to a blank account. Now the account with my character sis locked.
Afterwards they direct you to the REAL site, which has the "maintenance accounts" listed and where you can enter your code to the RIGHT account.
REGISTER HERE
https://secure.square-enix.com/account/app/svc/mogstation
Good luck
Edited, Aug 30th 2013 4:45pm by vahlmyth