It’s probably best if you make an issue on the Github repository for exact instructions, but if you extract the tar.gz (using 7-zip on Windows is probably best for that), the folder structure of the plugin should mirror the folder structure of the Coreform Cubit installation. So files in /bin go in /bin, /include goes to /include, etc. Cubit will load the plugin when you start up Coreform Cubit.