Can not download the PDF

[snippsat]

It seems it is better than before since the "print(p.content)" print much more content than before. And I haven't got any error message. Does this mean the login is successful?

You most look at the contend and see if it's the same content as logged in browser.
See if download link is in content or if you need to navigate more.

Learn to use Chrome DevTools or Firefox Developer Tools to look a content of a website.