You did indeed forget the key word there. It's cristal clear now, thank you.

I do have an account in the Apple Developper Program but it’s a free one. I’m just beginning to develop for the Apple eco system and wanted to reach a level where it would make sense before I enrol. Also, I’m not a professional developer, this is just a hobby to keep me busy when I retire in a couple years. Will I be able to play around with MusicKit with my free account, or would I have to enrol for that?