I'm trying to add a PDF into my ArcGIS. As I understand it is possible to change the PDF to a DWG, but I don't know how to do this.
If using a DWG is not a mandatory requirement, then it is possible to use the PDF To TIFF tool to convert your PDF to a format suitable for viewing in ArcMap:
Exports an existing PDF file to a Tagged Image File Format (TIFF). If the PDF has georeference information, the TIFF can be a GeoTIFF. These TIFFs can be used as a source for heads-up digitizing and viewing in ArcMap. Both GeoPDF and ISO standards of georeferenced PDFs are supported.
If your PDF has vectors in it, and you own AutoCAD, you can open it in there, and convert it to DWG or DXF while keeping all georeference if there is any.
Otherwise, there's the combination of tools pstoedit - ghostscript - gsview, which allows you to convert a PDF (with vectors) into a DXF. Although I'm not sure if this still works, I just remember coming across it before. I do know that it loses georeference though.