More and more people are switching from known NAS manufacturers to UGREEN NAS systems.
Until now it ist possible to install and run PMS through Docker. I used to have a Synology and the native PMS worked excellent. For me Docker is more complicated and not that efficient.
When will you develop a native PMS app for UGREEN systems and the UGOS operating system?
You do not use the UI to do this as this is not the debian environment, you need to ssh into the debian OS, and then you just install Plex as a debian application using the usual cmd to install a package:
wget [Plex download link]
sudo dpkg -i plexmediaserver_xxx.deb
etc..
I do not have a link per say, but if you google plex installation debian, I am pretty sure you will find some good videos or link that explain in details how to do this