Can’t load plugins on Mac

Looking in the Folders in Preferences, I can see that plugins go in Documents>MuseScore>Plugins. However, when I drag the downloaded Voice Colors plugin into that folder and restart MS4, it doesn’t appear in the program. I downloaded a couple of others a day or two ago, and they aren’t in that folder either, yet they are there (and work) in the plugins menu. So, (1) what did I do to make it work last time? And (2) how do I make it work again?