Medium Editor is a text editor, such as Advanced HTML Editor 3. It is not a CMS, nor it is Online Page Editor Add-on.
You use it the same way as any other HTML Editor out there - on your CMS forms. Just build your own CMS and login functionality for your users.
You can alternatively use it on the pages like: https://www.dmxzone.com/go/32933/using-app-connect-medium-editor-regions
So why not do it as a Database instead of doing it as HTML? So much easier. Unless I don't understand what you are trying to do?