Add avel as a git submodule.

cd your-zola-site
git submodule add https://github.com/kako-jun/avel themes/avel

Set the theme in config.toml.

theme = "avel"

Create content/posts/_index.md.

+++
title = "Posts"
sort_by = "date"
paginate_by = 20
+++

Run zola serve and check the site.