How to find the correct page for wget to download from?

I want to download all *.pdf files on a website recursively. What I could achieve so far is:

• Store the cookies needed for the login page with this question
• Download a specific file by copy and pasting the direct download link from my browser.
  Now I tried using the following command:
  wget --recursive --no-parent -A pdf --load-cookies cookies.txt https://example.com
  

But I just got some empty folders, which leads me to believe I didn't use the correct link. How can I find the correct link for the recursive download?