Based on my experience setting up a blog:

The default setup creates a root page "Home" and page "Blog" underneath. The apphook is on the "Blog" page. You can, if you so wish, modify the default behavior and have the blog page be your root (the BLOG_AUTO_SETUP and friends at https://djangocms-blog.readthedocs.io/en/latest/settings.html). You can also have the apphook page at root, and then it will be post listing by default. I don't think either way is right or wrong but depends on what you want. I ended up using the default setup and having a "latest blog posts" plugin on my main page.

As for the templates, the default blog template hijacks the content block on the apphook page. If your parent template doesn't have a content block, or you want more flexibility, you need to customize either the blog template or your parent template.

Sorry, I'm not sure why show_menu would fail without seeing any error messages or code.

Hope this helps!

@jasujm thanks for the very comprehensive answer, better than I could have done myself
I'm open to suggestion on how to clarify documentation to help people trying this app to set it up

Sorry but this is not helping. The setup is very confusing. I got to the point where I made the page, added the app hook, created a blog post but then page displays absolutely nothing. I can add various blog plugins to the placeholder in the template, but that doesn't seem right as every single page shows the same content (click "see more" on post, it changes url but content stays same).

Here's my default and only cms template:

{% extends "base.html" %}
{% load cms_tags sekizai_tags %}

{% block title %}{% page_attribute "page_title" %}{% endblock %}

{% block body %}
{% placeholder "content" %}
{% endblock %}

Config is

CMS_TEMPLATES = [
    ("cms/default.html", "Default template"),
]

What am I missing?

Here's my default and only cms template:

{% extends "base.html" %}
{% load cms_tags sekizai_tags %}

{% block title %}{% page_attribute "page_title" %}{% endblock %}

{% block body %}
{% placeholder "content" %}
{% endblock %}

Config is

CMS_TEMPLATES = [
    ("cms/default.html", "Default template"),
]

The content needs to be a block, not a placeholder.

I have added in #631 an improved setup documentation to address both the template changes and the steps required to have the blog on the home page