Hi,
I'm sorry to hear that you're facing trouble with it. It seems that your library is missing the Arnold materials for hips and ridges. Please copy the rc_roofing_arnold.mat from ..\Architecture\Exterior\Roofing\Tiles\matlibs to ..\Architecture\Exterior\Roofing\Hips and Ridges\matlibs. That should do the trick.
I hope that helps.
Best regards,