Can't enable plugins?

I've decided that I want to start experimenting with plugins in Musescore, but I just can't get them to work. I've tried downloading a couple plugins listed on the website, extracted the .zip files and moved them into the "Plugins" folder in the application, but when I go to the "Plugins" tab on the app they don't show up, no matter how many times I reload. If I quit & restart the app I get an error message that the app is damaged and I have to move it to the trash. What am I doing wrong?

I'm on the latest version of Musescore and running MacOS.