Upvote:-2
This is probably related to the Advanced Passenger Information. However, you should check with your airline.
Upvote:0
You need to put your passport number in that field, and at the airport, present both the boarding pass, passport and residence permit at the document check desk in order to get your boarding pass stamped.
Upvote:2
It doesn't seem like you have much of a choice at this point. Enter your nationality accurately, which means you will have to put in your passport information if that's what the system requires.
However, Ryanair requires that all non-EU/EEA nationals visit a special document check counter at the airport before going through security, where you'll present your travel documents (such as your Spanish residency card) and get a stamp. There are various reports of them being extremely strict about this fairly obscure requirement, denying boarding and forcing passengers to pay for new flights even if they didn't know this was required by Ryanair. So be sure to go to this desk and have your documents checked first.