Confused as to how related content works and how to make it work

What does this mean?

What does your config.toml look like?

Does your content have any categories or keywords in front matter?

Please post a link to the public repository for your site. See:
https://discourse.gohugo.io/t/requesting-help/9132

Include a link to the source code repository of your project, because we really need the context of seeing your templates and partials to be able to help you. It is trivial to do a quick git clone on your repo, then run hugo server in your project, to help you out. On the other hand, recreating your code from screenshots, or sort of guessing at it, is not.

If you can’t share your repository for whatever reason, consider creating a dummy repo that you can share, which reproduces the problem you’re experiencing.