From the WordPress Dashboard:
1. Go to Media Library Folders Pro, Folders & Files:
2. Click on catalogues in the folder tree:
3. Click on the Upload Files icon (in red below):
4. Click the [Choose File] button:
Browse for the PDF catalogue file, then click [Upload Image]. Once uploaded, you'll see the PDF file as below:
5. To get the link, click on the big, grey PDF icon (as above), and you'll see the link as below, next to Permalink:
6. Right-click on the link and choose Copy link address:
The link will be in the clipboard for pasting into that bit of the home page.