This deck uses Anki's spaced repetition to schedule musical listening, in this case of great classical music pieces. For how one uses Anki to do this, see this page (
http://scheule.blogspot.com/p/spaced-repetition-for-music-listening.html), which walks you through it.
The pieces included are all taken from a half dozen online lists I found of greatest classical pieces, such as greatest operas, greatest concertos, greatest chamber music, etc.
The deck does not include any musical files--it simply schedules what one listens to using whatever method they like. You can use Spotify, Youtube, an old dusty LP collection, or even your private in-house symphony orchestra, if they need something to do.