You need to download the LunchBox ZIP version. This has all of the individual Lunchbox files without the Windows installer.
Once downloaded, copy LunchBox.gha and LunchBoxML.gha to your /Library/Application Support/McNeel/Rhinoceros/6.0/Plug-ins/Grasshopper (b45a29b1-4343-4035-989e-044e8580d9cf)/Libraries folder.