I'm repeatedly getting an error after the payment screen when trying to book a somewhat complicated itinerary (built using ITA matrix, transferred to google flights, then open UA from google flights).

I'm not sure if this means there's something wrong with the payment (presumably they'd tell me if it's an authorisation issue), or if it's a website issue. (Note: fare rules allow buying in area 1, and I'm paying with a US debit card.)