Drop "GrayTech 2D" and "GrayTech 3D" folder in to:

on Windows:
C:\PLUGIN_FOLDER\u-he\TyrellN6.data\Support\Themes\NAME_OF_THEME\

on macOS:
(not sorted by plugin; plugins find theirs automatically)
Macintosh HD/Library/Application Support/u-he/Themes/NAME_OF_THEME/ 


Then right click on an empty space of the GUI and select one you want to use.

