Does this mean I have to get a US PS4 account?
Would I have to play it on the US account.. or can I play it on my AU account?
You can play it on any account, I think the only "draw back" if you could even call it one is you probably won't be able to buy extra points from the shop.
Correct me if I'm wrong but that was the case for me in FIFA 14 which didn't really bother me.