Thanks everyone. It turns out that I'm just super forgetful and apparently have 2 PSN accounts. I accidentally registers the code with the PSN account I didn't realize was the wrong one (or that I even had for that matter)

Thankfully I guess it seems the game is registered to my PS4 so I just made a "new" user with my real PSN account and it works now. Hopefully this won't become a problem later on but I'm sure with my luck it will be.