I want to add a certificate to on demand training, so when users watch a training they receive a certificate.
afctraining Sorry, GoToTraining Certificates are not available yet with Anytime Trainings.
Can I add my own certificate to a material attachment and attendee can access upon completing the recording?
afctraining Yes, you can make Materials available only after a GoToTraining session is complete: https://support.logmeininc.com/gototraining/help/create-and-manage-materials-g2t020015
So it works the same way with recordings in a catalog?
Yes, Anytime Trainings can have Materials and Tests just like regularly scheduled GoToTrainings.