Upgrading to Synology DSM 7 without granting read/write to PlexMediaServer

You cannot continue to grant user Plex permission to read the shared folders in DSM 7 because user Plex is no longer used (mandated changes for DSM 7).

Please read here and understand all the changes which were required then read the supplement (packaging - structure change which gives us as close to DSM 6 as was possible to do in the new DSM 7 platform environment)