Advertisements not showing up in thumbnails.

Hi, sorry for any ignorance here, but I’m still somewhat of a newb. I have the widget set up to include 3 advertisements in the 6 thumbnails I have, but I only see one, and it is for nrelate itself. I visited their website and noticed that I have “0” advertisers selected, but there doesn’t seem to be a way to select any, and I assumed that they would just be atomically (presumably real-time) generated as with google adwords. Am I missing something? Any help would be greatly appreciated. Thanks.

https://wordpress.org/plugins/nrelate-related-content/