I installed it some time in the last couple of months... WORKED fine on FF v54.0.1 and BECAUSE of the MOZILLA INSANITY scrapping the XUL/XPCOM extension system.. I have moved to FF v52.x the ESR release... for now.. and having installed Waterfox a fork of Firefox.. :D :D WORKS great there too!
EDIT1: new idea [feature request] ADDING - distinct ICONS to the context menu to make it a bit easier to differentiate between entries, AND - [hr] dividers to separate chunks of selections more more readability.. OH you already have a few... they area reather HARD to see though so maybe ADD more and make them BOLD/thicker??
EDIT2 (2017-10-03): adding url links for the version and beta version pages to the context menu... for rapid access of these web pages besides the default AMO Ext. page