Can you tell me where you found this mention? It should be removed.
Gary is correct that you can get this PDF file by downloading and installing Panorama 6, but that installation can be difficult on recent versions of macOS. Actually, reading Gary’s post he does describe a way to get the docs out the installer without actually running the installer. Anyway, no special technique is needed, the PDF files are still available as separate downloads. Go to this page:
and look for Where can I download Panorama 6 Documentation? You’ll find direct links to all of the PDF files that were included with Panorama 6, without having to actually download the entire Panorama 6 installer.
Now that I’ve told you how to get these PDF files, I would suggest being quite cautious with them. As Gary mentioned, a lot of the material in these files still applies to Panorama X, but there’s also quite a bit that has changed. So you might find them a bit frustrating – but at least you will be able to more fully appreciate how far forward Panorama has come in the past decade!