Until I see something, all I can do is smile and 
I need some kind of information. (any of the following which shows errors)
- A screen capture of errors from the package installation
- journalctl output showing errors as plex starts
- PMS logs (the ZIP file) of failures during playback attempts.
Any of the 3 will help.
I can’t even determine if this is a pre-roll problem or not until I see why the playback fails.
See my point?
a) Preroll fail (shouldn’t be fatal)
b) Can’t open video file ?
c) Can’t find codec ?
d) Insufficient space to transcode ?
There is so much which could go wrong, all of it easy to fix. I just need to see what instructions to give