SquareEnix created and runs the game. You have to make an account through them anyway.
Just to be sure; this is the US site
http://na.square-enix.com/us/home ... since you didn't provide an actual link and you didn't put the '-' in there.
The game is fun, take your time, enjoy it. Takes a bit of adjustment; but their 2nd coil of bahumut fights are pretty intense, I know someone whose group broke up recently from 1st coil turn 5. So, the game is good for fun play and intense play. It looks amazing; seriously, some zones, especially at night, have a real O.O factor to the atmosphere they created.
Have fun.