the plugins dotn go into the c:/ lotro directory
it should be in the documents folder
so basically as example the Vitalbars plugin:
C:\Users\[yourprofilename]\Documents\The Lord of the Rings Online\Plugins\Faflaf
The Pluigins directory needs to be created by you.
The Faflaf folder is the one you see when opening the rar file.
personally i'd prefer it if authors would name the folders with the plugin name rather than theirs
but hey.