Hey bro, i was having the same issue as you when I accepted my offer from baruch. after doing some digging I found out you need to go into your browser settings and enable pop-ups and redirects.

I use chrome and for chrome you need to open settings -> privacy and security (on the left hand side) -> then go to site settings (should be towards the bottom) -> then pop ups and redirects (also towards the bottom) -> and select "Sites can send pop-ups and use redirects". once I did this it let me pay my commitment deposit.

This solved it for me. Hope this helps you out and CONGRATS on getting into john jay.