Separate audio files for each track can be saved to your device or to iCloud.The STEMs can then be used in a DAW of your choice, for example, when you want to remix a song or extract samples for your own cover versions or compositions. You can use them for your own practice, for yourself, and at home. Using them anywhere else will likely require sync and/or master use licenses (https://www.wikihow.com/Get-Sync-Rights). This feature is only available for your own songs files, and songs selected from your library. It is not available for song previews.