Using purchased files

This depends on what sort of file it is.

Carbide Create imports DXF and SVG files (and of course opens its native C2D format).

Pixel images may be imported to be placed on a background layer to be re-drawn, or image traced: Carbide Create - Image Tracing

If you have a Pro license it is possible to import STL files to add them to the 3D model, or pixel images may be imported as depth/height maps. For STLs see:

https://carbide3d.com/hub/courses/create-pro/3d-tool-import-stl/

and also see

and

note that only binary format STL files may be imported: