Install
OpenMusic installs from an APK on Android 7.0 and up, and from an installer on Windows.
Open the latest release and tap the APK file.
Android asks once to let your browser install apps. Allow it for this download.
Tap the downloaded file and press Install.
On first launch OpenMusic explains the optional permissions: notifications and music access.
The Windows app has its own installer and steps. See the Windows page.
The source code is public, with every release on GitHub. View the repository.