I want to select the top face and extrude up. It gives me an error when I try to do this.
I can’t upload stl files here.
Hello! STL files in CAD software can mainly be used as references. We have a limited toolset that can be applied on mesh files, let me share the relevant article with you:
Please refund, I do not want this software.
Sorry to see that 
Please open a ticket and let us know what email address you have registered your Shapr3D account with, it is necessary for initiating the refund.