Hi Andrea, the first PDF link is being treated as an image because it uses the basic “fancybox” which is limited to images or inline content. Try class=”fancybox-iframe”…
The second link uses “fancybox-pdf” and should work but doesn’t. This is probably related to the fact that your theme includes jQuery 3 instead of the jQuery library that comes with WordPress. The theme version is not compatible with Easy FancyBox. Is there a theme option to disable the custom jQuery library?