I finally found out that you're supposed to enter the 12 digit code into 'Redeem Codes' listed under Playstation Store. I'll admit that I don't remember all of the exact steps to take and won't be able to check until I get out of work. It took about an hour to download the game (which confused me since I have a physical copy, but whatever). I saw my Early Access stuff and characters listed and that there was a 'Create New Service' button below them. I avoided 'create new' like the plague and just clicked submit. Everything has worked fine for me since then.