That is ridiculous -- KindleUnpack doesn't convert anything.
calibre already has a conversion feature, you can use that to convert from AZW3 to PDF. I don't know why you would want to, since PDF is a terribly inferior format, but you certainly can.
As for
AZW4 -- it is already a PDF, just hidden inside a Palm Database, the same as the HTML and images which are wrapped in a Palm Database to create an AZW3. KindleUnpack has one purpose only -- to
extract the contents of a Kindle format book from the underlying Palm Database wrapper.
AZW3 --> extracts to folder full of HTML and image files and stuff.
AZW4 --> extracts to PDF.