Good evening @dwagner,
It seems that you have a memory problem where @afischer might give you a little more information.
@afischer posted a good answer to your question a while ago:
The hexahedral meshing is not based on so called rich geometry formats as for example *.step or .iges, but on triangulated geometries like e.g. *.stl. In general you should not care about this at all as the triangulation is done automatically prior to the meshing. In some cases, if the geometry model is not "clean", the triangulation can not be done properly and there might be small cracks or duplicated triangles. The meshing is in general very robust in regards to those defects.
Please also consider: CAD Preparation
If you still encounter any problems feel free to ask me.
Best,
Jousef