You can check-in and retrieve your boarding pass via your smartphone with the free Aer Lingus mobile app, available for iOS and Android users.
If you have any difficulty accessing your mobile boarding pass link, you can go to the online Aer Lingus check-in » and reprint your boarding pass from there.
If you are already at the airport and cannot access your boarding pass link, you will need to go to a check-in counter and obtain a paper boarding pass.