If you have an Economy Light ticket, there is a charge of 25 eur to print your boarding pass at the airport. Therefore, check in online from home. For tickets on more expensive fares, you can check in at the airport for free.
Online check-in is available from 24 to 2 hours before departure, also with mobile check-in. Some airports don't allow online check-in, see Condor's website for a full list.