My friend sent me a zip of his plugins folder. He is on Windows. I am on macOS. I unzipped the file he sent me, and moved all the folders inside of it (names like Fundamental, VCV-Recorder, etc.) into my ~/Documents/Rack2/plugins folder. I chose to replace Fundamental.
Rack still doesn’t seem to think I have any of the plugins installed.
Just to clarify, the plugins are executable code. Just like you can’t download a program for Windows and run it on a Mac, the same is true for VCV Rack plugins. They come in 3 flavors: Windows, Mac, Linux.
You would be far better off subscribing to the plugins you want on the VCV library and then downloading them from within the Rack application like everyone else does.