There is a free option, which I use. If you want to stream locally, then paying for it is unnecessary.
The differences between free and premium are noted here (just scroll down to the table): https://www.plex.tv/features/
It’s pretty simple to set up:
- Create a plex account
- Install plex server on your My Cloud (you can do this through the website or the app on your PC). Once it’s installed, set it up
- Install plex client on your device, and sign in
- Stream stuff :D/