If you bought it off PSN, follow the instructions and download the 7gb file. You will then have to link SE and PSN accounts. After that look under Account Management >> Services List and check on your FFXIV ARR status. It should be there. PSN seemed like the easiest way to get this game from what I read. Good luck!
Edit: By buying it off PSN, I believe you eliminated the need for the code. If your account says you have early access, you're golden.
Edited, Aug 23rd 2013 6:35pm by RhuarcAllah