Just checkin for free on your phone and use your phone as a ticket. I fly with Ryanair often enough and honestly wasn't even aware there's still a fee like that.
As other said here; if you book via a 3rd party and you have very little experience (you are a holiday traveller), you don’t know that you have to or how to login to the Ryanair site as they don’t tell you. So when you arrive at the airport you have a nice expensive surprise for the family.