Can only buy on Battle.Net, but they don't allow refunds for black ops 4 apparently. I'll try again tomorrow but it appears as of now I got scammed. I forgot I had to pay an extra $50 for the fucking battle pass to get the DLC so I wanted my money back to go play a different game. No refund. Looking around, you can apparently refund other COD's no problem but I've seen a persistent issue of it being non-refundable across other threads.
TLDR no refunds on the game if you're not sure, don't buy this horse shit.