This is a versatile Playlist Manager and MP3/M4A/FLAC tag Editor.
NOTE:
Android playlists are deprecated in API level 31.
Google will keep the current functionality for compatibility reasons,
but will no longer take feature request.
Google do not advise adding new usages of Android Playlists.

Apart from the usual functionality of creating playlists from your music, there are many unique features such as creating not only android but also .m3u and smb playlists.
In addition, it offers a level of integration with Poweramp™ music player.

To get the maximum from this app, ensure that all your tags are suitably completed.
Comprehensive is provided on:
http://www.theo.klinkweb.nl/
and
https://youtu.be/3std8gu7JAs