c4d to dwg conversion represents export of CINEMA 4D graphics (.c4d) to AutoCAD DWG format (.dwg), either for 2D or 3D purposes. If you have access to CINEMA 4D, you might be able to convert c4d to dwg by first exporting the to DXF and then using any of the available dxf to dwg converters.
Without CINEMA 4D you will have to rely on some 3rd party c4d to dwg conversion, for example PolyTrans-for-CINEMA-4D.