I have a Program that uses the Music of the User. Currently the User just can open the Files to use these in the Program. But on smal devices the user maybe stores his music in the cloud and uses streaming.
Is threr a way to acces his music from XBox music (including his Onedrive Music) without downloading the files to his device?
You can access the a user's OneDrive Music folder through the special folder endpoint. There are more details at https://dev.onedrive.com/items/special_folders.htm.