As far as I can see, the tutorial does not include instructions on how to enable the autodoc extension for Sphinx in the first place. The file conf.py has to include extensions = ['sphinx.ext.autodoc'] (see https://www.sphinx-doc.org/en/master/usage/quickstart.html#autodoc) to correctly render the autodoc directives.
I would suggest adding this information to sphinx-config.rst. I'd be happy to create a pull request to fix this.