To download a contact sheet for a folder or album, navigate to the information page for that folder or album by choosing it in the folder tree and selecting the "View Detail Information" button.

Then, select the "Export Thumbnails as Contact Sheet" button.

Next, you will have the option of the PDF name and the number of image thumbnails per page and what metadata information you would like to include.  After selecting from these options, select the Apply button

After the contact sheet has been created, you will receive an email with a link to download the file.