Clone the repo
composer install
Configure your local web server to serve the web directory as a site
mkdir web/sites/default/files
cp web/sites/default/default.settings.php web/sites/default/settings.php
chgrp www-data -R web
chmod g+w -R web/sites/default/files
chmod g+w web/sites/default/settings.php
Create a database
Go to the local url and run the web installer (choose "Standard")
drush config-set "system.site" uuid "0c85ec7c-68f9-419f-92bb-d9a3a256ca23" (this allows you to import & export config to other sites built using this repo)
drush config:delete shortcut.set.default (it always complains about the shortcut set already existing when you try to import the config)
drush config:import --source ../config
Appearance->Settings->Bartik and just save what's in there (to regenerate css)