HDRI Suite Installation Guide
HDRI Pack Installation:
To install a Greyscalegorilla HDRI Expansion Pack, please drop the expansion pack folder into your “Preferences/MAXON/CINEMA 4D/plugins/HDRI Browser/Packs“ folder.
You can find this folder by launching Cinema 4D. Go to ~Edit ~ Preferences and in the bottom left there will be a button to open the preference folder. Then go inside plugins ~ HDRI Browser ~ Packs.