Basic documentation's for suckers
I think maybe you should put all 3 locations mentioned for Windows, Mac & Linux into a sticky. Definitely worth it. Took me hours of stuffing around to finally work out where everything was.
I definitely recommend changing the default install for Linux by the way.
If anyone is having issues getting your head around the 50 deep folder structure in 2 separate locations do this:
Stop the plexmediaserver service (for Fedora it's: systemctl stop plexmediaserver.service)
#mv /usr/lib/plexmediaserver /opt/plex
#mv /var/lib/plexmediaserver/Library /opt/plex/
OR you can just delete and start again: #rm -rf /var/lib/plexmediaserver
#chown -R name:name /opt/plex (change name to your username)
Edit these two files (again this is Fedora, but you will have either both, or one of them depending on your distribution):
Change the /usr/lib/plexmediaserver to /opt/plex
Change the /var/lib/plexmediaserver/Library to /opt/plex/Library
Change the user and group from plex to your username for both of them.
Save and start the service, and then run a status on the service (Fedora: #systemctl status plexmediaserver.service)
Now things are a little more logical, and easier to get to as everything is sitting under one folder now.