Co-Author Plugin with Author Bio Box

I know there are a lot of post about how to get this to work, but I’m still at a lose and the ones that seem like they could help, the comments are closed. I’m trying to get multiple authors to show in their own Author Bio Box and at the top of the Blog post. I’ve read the instructions from there: https://vip.wordpress.com/documentation/incorporate-co-authors-plus-template-tags-into-your-theme/, but still don’t quite understand which .php file I need to add code to. Single.php or class-author-bio-box-frontend.php. These seem to be the only two files that I can find where it mentions author in the code.

Any help that can be provided to me would be greatly appreciated. I’m learning php on the fly, but feeling stuck at the moment.

Thank you
Kim