This Brush is only available to user who have the Sculpting System. That is all users of the Studio version of Cinema 4D and also all BodyPaint 3D users.
This brush works best with the BodyPaint layout. You should create a new layout based on BP3D Paint and add this brush to it. The brush works with the BodyPaint system for changing colors and also supports multi channel painting.
You can still use, and its advisable to use, the Material View for selecting the channels and layers that you wish to paint on.