Keep getting "parse image error" when trying to load files in Luban

I’m trying to get parts into Luban to cnc cut. I’ve tried .stl and .step files. What kinds of files work in Luban that won’t give me the Parse Image error?

Hey, stl´s won´t work, they are just for 3dprinting.
Here is a guide to do some engraving:

Hope this helps!

Thanks for the info!