Where did you install the Plex Media Server?
-
If it’s running on the Windows machine where you’ve mapped the Synology network share to
Z:\Main\Plex\Movies, you should be able to select that folder from the „add folder“ menu. -
If it’s running on the Synology itself, you’ll need to find the local path as it’s known inside the NAS. Usually this is something like
/volume1/Movies/— you should be able to pick this from the list of top-level folders showing on the left side of the folder selection.- If Plex doesn’t see your media after successfully adding the folder this is likely a permission issue. You should be able to allow the Synology user
plexto have access to the movies folder in Synology‘s system settings / command center (Manage Shares > Edit Permissions)
- If Plex doesn’t see your media after successfully adding the folder this is likely a permission issue. You should be able to allow the Synology user
Edit: There’s quite an extensive collection of Synology related guides on common caveats (and some more tricky use cases you might run into in the future). I find that quite helpful 
