Hi Houthuyst!
It looks like no one has responded to your question. Here are a couple things that might help others answer your question:
1. Are you trying to access music that was purchased from the iTunes Store, Apple Music downloads, or music that was synced using iTunes?
2. Are you seeing an error message? If so, please tell us exactly what it says.
3. Are there any troubleshooting steps that you've already tried?
Cheers!