Copy the folder with the mats from Runtime:Libraries:Materials to Runtime:Libraries:Pose.

Rename the .mc6 files to .pz2

Open each .pz2 in a text editor.  I use Notepad++, which can edit multiple files and let you make global changes in all of them.  The 6th line in each will read:

mtlCollection

Change that line to read:

figure

Save the files and start DS, and it will now be able to see them.