The instructions Krytos listed sound like the instructions for how to register a physical copy of the game. For console players, if you order the physical box (either from SE or a third party retailer), then there are codes you have to add to the PSN in order to tell Sony that you bought it (or ordered it in the case of the preorder code). But if you buy the digital version directly from the PSN, you don't need to tell them you bought it. They already know about the purchase, so it should be applied to your account automatically, without any codes involved.
(This also means if you have multiple PSN accounts or subaccounts, you need to be sure you're on the right one, the one that your FFXIV account is associated with, when you purchase the game from the PlayStation Store. The account you buy it from is automatically the account it's registered to.)