I'm having a similar problem. I have downloaded LyricsReloaded, put the .dll in MusicBee's plugins folder and followed the ReadMe.
On the bottom right pane of the Music Explorer screen it shows Track Information and if I click it I can select Lyrics so I guess they're working but I want them in the right-main pane so I select Arrange Panels but Lyrics doesn't appear in the Available Elements box. I've worked out how to display them in the Now Playing screen but I want them in either Music or Music Explorer in place of Top Tracks.
I must be doing something wrong but I can't work out what for the life of me. Could you point me in the right direction please?