Unfortunately the YouTube API is not providing endpoint to retrieve your YouTube / YouTube Music saved playlists made by other users / YouTube.
However, there's a solution to be able for Soundiiz to retrieve these playlists. Follow these steps:
- On YouTube, go to "Your Channel" in your profile menu
- Once on your channel, select "Customize Channel"
- On your Channel page configuration, select the "gearing" icon (Channel Settings)
- Uncheck "Keep all my saved playlists private" setting
That's all ! On Soundiiz, connect your YouTube account and select this same channel or simply reload the Soundiiz application if you already have connected your account.