Place the unzipped ‘Maxwell’ folder in your Cinema 4D ‘plugins’ directory such that the structure looks like this:
+ Cinema 4D
+ plugins
+ Maxwell
+ doc (folder)
- Maxwell for Cinema 4D.cdl
- Maxwell for Cinema 4D.cdl64
- Maxwell for Cinema 4D.dylib
- readme.txt
+ res (folder)
+ vcredist
-...