The issue you are describing here looks like a problem with your configuration of the PlayOnline Viewer after a fresh reinstallation. In order to log on, you are required to have at least four pieces of information. Thanks To Sarick for the detail.
PlayOnline ID:
PlayOnline Password:
Square Enix ID:
Square Enix Password:
If you are missing any of this information, please check the SQUARE ENIX Support Center for instructions on how to recover lost information/configure the PlayOnline viewer.
The SQUARE ENIX Support Center can be found at this link:
SQUARE ENIX Support Center