Once your PDF catalog is ready you will get a notification e-mail letting you know that the catalog is ready. But the e-mail doesn't include the link to the PDF, you will find the link to your PDF in your control panel.
This is where you will find the link to your PDF in your control panel:

If you have any other questions relating to PDF catalog feel free to leave here a comment.
Sincerely,
-Tzipi.