It's really simple in Pro Metronome.
You can just tap the zoom button on the playlist interface to enter "full-screen Playlist Edit mode".
For iOS users, you can tap the "Edit button -> Share -> as Link" to export all Playlists or certain songs as links, then share with your friends or backup it to the cloud.
For Android users, you can "long press the list items -> Action bar -> Share" to export certain songs as link, or "Action bar -> Share" to export Playlist as link, then share with your friends or backup it in the cloud.
Also this video could help: