Create seperate users on my plex media server

Precisely.
There are some precautions to make, to make the communication between the NAS and the PC work smoothly:

  • Don’t let the NAS spin down the drives when idle. They use very little power for maintaining their spin and they’ll live longer that way.
  • I assume you’re going to use Windows on the PC. Create identical user name and password on both the PC and the NAS.

See Verbatim Powerbay NAS with Plex media server for more info.