I've just wasted sooooo much time on this and I want to share my experiences!
im a ps3 owner, not ever been a pc gamer, so if you are a pc pro, look away now, it will probably just confirm every prejudice you have against us great unwashed!
Ok, here goes!
I knew I needed a square Enix account, so I registered, linked my game and all seemed straight forward, until I hit two problems.
1 I put in a user name, same as my psn account name, sachoje, and it happily appears at the top of my square Enix page... But it if dig around I find that in other places my user name is sachoje8, when I look at the games I have linked to my account and in a few other places greyed out in info boxes. To log on on my ps3 I had to use this second name. At no time was I told that sachoje was not available.
2 the one time password box, again I spent a while on the Enid website tring to register my phone to get me this password, but the app was not available to me to down load! Getting more and more frustrated with it all I then found out that it simply is not needed! Just leave the box blank!
this has been written on my iPad, sorry about the auto correct (Enid for enix) and some missed capitals and such. Paul