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:
If you customize the layout of your channel:
- Sign in to your channel on YouTube.
- In the top right, select your profile picture Settings .
- On the left, select Privacy.
- Toggle the options next to the individual activities.
If you don't customize the layout of your channel:
- Go to your channel.
- Under your channel art, click Settings or .
- Under "Privacy," turn on or off the individual activities.
More details here: https://support.google.com/youtube/answer/6336092
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.