Display ads by cat? How?!

Hi,
it looks like your theme is conflicting with the WPAdverts taxonomy display, there are two ways to have it fixed:
– create a taxonomy-advert_category.php template file as explained here https://wpadverts.com/documentation/child-themes-and-templates/ in “Custom Taxonomy Template” section.
– install Alt Term Links snippet https://github.com/simpliko/wpadverts-snippets/blob/master/alt-term-links/alt-term-links.php, how to install it you can read at the bottom of the page here https://github.com/simpliko/wpadverts-snippets/

The first solution is better in terms of SEO (that is it will allow you to have SEO friendly Advert Category URLs indexed) but requires some PHP and WordPress API knowledge, the second solution requires just installing the snippet but the Adverts Categories taxonomy pages will not be indexed in Google.

After following the tutorial, theme is still unable to load the ads under specific category. What might be the cause?

It is hard to tell as each theme is different, can you paste a link to a page where you are having this problem? and let me know what theme are you using?