[Plugin: Yet Another Related Posts Plugin] template system not working?

Im building a theme for a client using html5 boilerplate as a parent. I have the widget in place. I try reaching the developer’s website, as it has been unavailable for days. I’d like to show the excerpt on the widget, however that option in the backend does nothing. In documentation I read that I should copy over the files in the templates directory to my theme’s main folder. Is that the parent theme folder, or the child folder. Also: what file displays the widget? I have tried various options, none of which seem to work. Anyone?

https://www.ads-software.com/extend/plugins/yet-another-related-posts-plugin/