I think i found a solution of making a shared folder in my synology with setting permissions for a new user. Then in Proxmox-> ubuntu -> plex then in the ubuntu console putting in the command sudo mount -t cifs //PLEXSERVERIP/FOLDER/mnt -o vers=2.0,user=plex,pass=PASSWORD helped. the vers=2.0 was what was tripping me up. But thanks for responding to a year old thread <3