UPDATE: Disregard! I found the option to link to the URL field in the right hand pane after selecting the thumbnail.
In my “Newsletters” CSM collection I have URLs to the newsletter PDFs in the URL field, and the PDFs themselves are in the site files, but nothing appears to be hyperlinked. I would like the thumbnail image and the title text to both be clickable. How do I accomplish this? Note: I have the same set-up on another site, and the URLs work fine, although they point to HTML pages, not PDFs and they are in Wix, and for this site I’m using WIX Studio.