Yes, the .RBZ file add-on must be loaded in a different way than drag and drop to the plugin folder. It depends on what version of SU you are using.
If you are using a newer version of SU (last few years) then click on window > extensions >install extensions is for installing .rbz files.
Simple .rb files are placed in your plugins/ directory. The exact location depends on SU version and operating system. For SU up to version 8, on a Mac, they go into either /Library/Application Support/Google SketchUp 8/SketchUp/plugins/ for system-wide plugins or in $HOME//Library/Application Support/Google SketchUp 8/SketchUp/plugins/ for personal plugins. Change "Sketchup 8" to whatever version of SU you have.
For newer versions of SU, I think you use "Sketchup" instead of "Google Sketchup".
You can also open the Ruby console and enter the command Sketchup.find_support_file("Plugins") and you'll find out for sure where they go.
Anyway, once you've copied the plugin to your plugins/ directory, quit SU and restart it.
It's actually pathetically easy to convert a .rb file to a .rbz file. Just place it inside a .zip file and then rename the .zip file to .rbz. If you do this, then you can use the window > extensions > install extensions menu item to install it and after that, it's easy to disable it or remove it. And you don't have to restart SU
-- Sun Apr 16, 2023 3:13 pm --
I thought the .RBZ is just a .Zip file and can be unzipped then added by "Drag and Plop".
This is true if you have RBZ Plugin that is compatible with your version of Skectup