Sketchup is both super simple and yet also has many quirks.

File Won't Open in other CAD

Sometimes Sketchup will make a version update and other CAD software can't open it. Portland CNC's version of Rhino will open 2015 or older Sketchup files.

Sketchup files with Curves are Faceted 

Based on how Sketchup creates model forms - 2D or 3D - all curved objects will be faceted. There is no quick fix to this. To machine smooth shapes the model will need to be rebuilt in another CAD software. We recommend Fusion 360.

Imported Sketchup Files are Mesh

When importing Sketchup into Fusion 360, the bodies will import as mesh objects. This is typically not useful. Portland CNC often uses Rhino to import Sketchup files (2015 or older) which will import as proper solid bodies (still faceted).