You really need to provide some more information....
Set up S3D so as to give a result that fails....and then export a Factory file...File dropdown==>Save Factory file.
This file will include the model AND your settings.....which will probably what needs adjusting! Not knowing your settings, its impossible to suggest what to change!
Looking at the stl file in a viewer, I can't see where you would wany any supports. The outside wall is angled well inside the range where support is not required...at least with it standing on one of the faces