Random question- I was at my Mac and in email and I tried to save a pdf from an email attachment into my files that you’ve helped me set up on the Mac. For some reason it won’t save - clearly I’m doing something wrong. Any tips?
___________

I'd first try to simply drag the attachment to the desktop. Moving something to the desktop gets it out of the application (in this case mail) and sometimes gives the computer a better handle on the file as you move it or do other things with it later.

Next you can try using the toolbar to download the attachment. Below you'll see a shot of the toolbar. Notice the paperclip denoting the email has one attachment.


Another idea is to right click and save the attachment.

If none of these work, the next step I would try would be to log into the webmail account (for instance, iCloud.com or gmail.com) See if the attachment is retrievable there. If you still have issues with the attachment even on the webpage, then there's most likely a problem with the attachment. Request the sender resend.