Show us the error dialog. 😒
As a guess...
You probably don't have sufficient access rights to the Sketchup 'plugins' folder.
Ensure that these are FULL [read/write], then retry installing the RBZ file through the Preferences > Extensions > Installer button, or use thomthom's API equivalent 'Simple-Plugins-Installer'...
Note that on a MAC the correct plugins folder is the one in the Lib of the root HD - NOT the 'user' equivalent [assuming you let SketchUp install itself in the default folders and didn't mess with it during the app's installation etc]...