After installing the Learn Ghost Theme, you should create a page for Topics and make sure you select the custom template.

https://support.themeix.com/wp-content/uploads/2022/08/image.png

In our theme we added page-topics.hbs so if you use different name it will not work.

How to change topics page URL in Learn Ghost Theme?

To change the topics page URL. You should create a page first and then rename the file page-topics.hbs with your new page name.