STEP is actually a CAD interchange format, you are probably thinking of STL for 3D printing. They probably want STEP as they can very accurately take the measurements needed for that type of file, its also quite Universal so almost all CAD software can read it, its the CAD equivalent of FBX…
If you don’t manage to find a solution in SketchUp you can use a 30 day free trial of Fusion 360 to make the new export the file pretty quick: Download Fusion 360 for Free | Free Trial | Autodesk