If the Jooki app reports that the storage is full, additional content cannot be associated with Jooki and you will have to remove some tracks from Jooki.
To free up space, first delete playlists, then remove the "unused tracks" coming from those playlists. To remove unused tracks: open the “Unused tracks” playlist, select the track you want to remove and click the Trash icon. Then click “Delete track” in the confirmation box.