@hilodfulaidien, welcome to the Rockstor community.
If I understood correctly, you want to use the Plex RockOn on Rockstor, however all or part of your library resides on a windows machine, correct?
If so, you will likely have to mount the windows share on the Rockstor box file system, so it becomes visible as a local folder. If you google a bit you will find instructions like this:
You might have to play around with the share settings on the windows machine to ensure that you can read it correctly, etc.
I have another brand of “music player device” like a “sony walkman” and I need to sync my music library on this device. I won’t always be in range of the wifi signal.
At the same time, I need to access streaming media on my “personal PC” with a DLNA client.
At the same time, I want to open Ebook with “PDF reader” on my “personal PC”.
ALL music and ebook, other docs are stored in a “MyLib” folder on the NAS.
The problem is: I can only select the “Shared” folder (which contains MyLib), and I want to select the Music folder in MyLib.
Ok.
I don’t know about Syncthing, but in Plex one would drill down into the “data” folder which is the one you originally mapped the entire share containing ebooks, music, etc. to during the Rockon setup, to select the specific folder that you want to e.g. represent your music library, e.g. like this:
Checking on the Syncthing configuration, it seems that the external share (containing MyLib for example) is mapped to this mount point inside the Rockon: /home/syncthing/Sync
So, I would assume that in the configuration you can select any of the sub-folders that you will now see under that directory and should have the ability to select things like /home/syncthing/Sync/MyLib/some_folder/some_other_folder/... but since I am not using this Rockon somebody else would have to confirm that behavior.