I was quite excited when I came upon this. I installed the package and currently it is running as enabled under services(Add ons-->My add ons-->Services). But when I go to manage through the web, I am not able to access. I have managed a previous PMS through the web interface(IP:32400/web). I can ssh into the kodi box, remote to kodi via web but I just can not able to access plex. Any troubleshooting tips?
Do you see port 32400 open and listening when you run netstat?
LibreELEC:~ # netstat -an | grep 32400
tcp 0 0 0.0.0.0:32400 0.0.0.0:* LISTEN
LibreELEC:~ #
If yes, then that means the PMS started successfully.
If no, then that means the PMS failed to start. Try rebooting. If a reboot does not fix the problem, try un-installing the addon, deleting the associated addon and userdata folders for PMS, rebooting, and re-installing the addon.
Also make sure that the addon is a match for your architecture. This addon is meant for 64-bit platforms, not ARM (Raspberry Pi) or Android.
If after the above steps, try reffering to this post on how to further troubleshoot PMS issues.