Sometimes, you get files from a consultant in DXF/DWG format that do not import well into Vectorworks. Often the issue is that the files are the wrong format (too recent). You really want the files saved in an older version of AutoCAD so your version of Vectorworks can read them.
You could contact the sender and ask them to re-send the files, but please save them as an older version of AutoCAD, please. That might be awkward, so I have another way.
There is a free AutoCAD file reader called DraftSight. It will allow you to read, write, and edit the AuotCAD files. It will also allow you to save the AutoCAD files as older versions of AutoCAD.