While connecting Plex to Soundiiz, you can, at the first login step, specify a "Username" configuration (or leave it empty to select the default user/admin), which could be very useful if you want to access music playlists for a specific user in your Plex Home.
Be sure to fill in the proper username in this "Username" section (respecting the case) before moving to the following steps, in the Plex.tv login step.
This Plex Home Profile must not have any PIN code or password to be connected correctly to Soundiiz.
Also, be aware that we cannot upload playlist covers/posters/images for such manager Plex Home users due to a Plex limitation.