The PlexMediaServer shared folder is owned by user PlexMediaServer.
You must be VERY careful if you modify anything because there is no way to correct the ownership via the GUI.
I made the share accessible to allow backups (primarily)
Please review the Release Notes posted here in the forum.
The limitations are because of DSM 7. DSM 7 has removed ALL administrator capabilities for applications. I , as package author, don’t even do the actual install & setup anymore – DSM does. it also allocates and grants access to requested resources if they are available. It’s very ugly.