Can't figure how to upgrade to the PS4 version now that the campaign has ended.

I've been playing FFXIV on PS3 for months now, but yesterday I bought a PS4 and the hard copy PS4 version of the game. I can't log in or anything, and the only thing I can find online to help is about the upgrade campaign, which has ended. I've been trying to figure it out for hours. When I go to MogStation and click Add PS4 Licences, it says this:

"Add PlayStation®4 License

Playing on PlayStation®3 or PlayStation®4

In order to play FINAL FANTASY XIV: A Realm Reborn on the PlayStation®3 or PlayStation®4, you must first either purchase the digital download, or apply a registration code through the Sony Entertainment Network. Please note that PlayStation® services are not accessible through this website.
Upon completing registration and installation of the game client, start the game and follow the on-screen instructions to log in and add your desired platform to your Square Enix account."

I don't understand what to do. I've gone to the PSN Store and entered the registration code, and I still can't log in. Please help me.