Doesn’t work

I’d love to have a plugin like this but I can’t make it work. Best I can do is make a list of categories, but I can’t get it to list individual posts within a category. Tried everything. Nothing works. Not even sure if it’s supposed to display individual posts in a category. There’s no information in what might be laughlingly called ‘Documentation’. I spent a large chunk of my day trying to make this thing work and it simply does not work.