Bank of America Credit Card Points Redemption

I have 30k sign up bonus points which I can redeem for $300 OBC (which I’ll probably do for my upcoming cruise in June) but I also noticed there’s an option to use 25K points for stateroom upgrade. I tried to read the terms and conditions but it doesn’t really help. Would you happen to know how it works? I booked with a 3rd party site (interior cabin).

When I try to simulate, it just asks for my Booking id but it doesn’t provide any details as to what’s gonna happen.