空港カウンターでのチェックイン

も可能ですが、、、
www.ryanair.com
Airport Check-in Fees
Airport check-in is available but charges will apply. Customers who have not checked in online will encounter an airport check in fee, which is £/€55 per passenger. If you have checked in but you have not printed your boarding pass, you will be charged for the boarding pass reissue fee, which is £/€20 per passenger.

55￡払うのなら、FRしか飛んでいない路線ならまだしも、複数飛んでいて価格だけが魅力な場合には、納得できるのでしょうか？スカイスキャナーから誘導されたのでしょうが、そもそもLCCに乗るのに第三者の手を介在させることは欠点はあっても、利点はあるのでしょうか？

Don't book Ryanair flight tickets through a third party
If you do book through a third party agency like Kiwi, they will lock you out from ability to check-in or check your reservation directly on Ryanair website. What they do is they change your email address to their internal address to purchase your ticket and before the day of your departure, they check in for you and send you your boarding pass in email attached as PDF. If you are EU citizen and you would be eligible to get mobile boarding pass, forget about it. You will be locked out from this feature and possibly many other useful functions.

Don't book Ryanair flight tickets through a third party - That's been the long standing advice on this forum for all airlines.

そんなことをするとは知りませんでした。今後の教訓でしょうね。