urgent help with reinstalling the game on PS4

I'm just about to upgrade my hdd to a much bigger one, so I'm gonna need to redownload everything (urgggh).

I just thought about it and I remembered that when I got ffxiv on ps4, I got it via the free upgrade system. This means that according to the PS store, I never actually bought the game, so therefore I'm not sure if I'll be able to redownload it without buying it again (which would be ridiculous!!)

Has anyone else done this, and if so how did you get around this?

Edit. I've checked and I still have access to the beta. Would it be enough to install this then install the heavensward client to install all of the updates? I'd like to try and do the install this weekend, but I don't want to screw myself out of playing until I can contact SE during the week.