The problem isn’t you.
You made one mistake which, if you’re new to Plex & Synology, won’t know unless you read the installation & setup FAQ.
Bottom line:
- Do not use the Synology-provided :
video, orphotoshares. - User
plexcannot get access no matter what you do. - Synology claims exclusive access
The Solution:
- Create a “Movies” share
- Create a “Television” share
- Create other shared folders as you need
- Move your media into those shared folders.
- Grant user
plexpermission to read them - Point Plex at those folders in your Library section definitions.