Mine glitched as well as the saved card had changed exp and ccv code at some point. Still got in and have already got my cards. But I was refreshing constantly and got in at 12:01 on the dot.
I don't think they'll add more. It said while supplies last.
Use the cards right away, hackers can get into your emails and use the cards before you. Happened to me last year and it took months to get my funds back.
I spent a couple minutes trying to stack a Rakuten cashback but the purchase wouldn't go through for some reason. I eventually gave up on the cash back and was able to snag 2 cards.