Huzzah you found the repo for the site!
Clone this repo, point your terminal to the project location are follow the next steps :)
All PHP depencies are managed using composer & the browser assets are managed using Bower, so assuming you have that installed just run:
composer install
bower install
I built this version of the site using PHP 5.4's built in server, so in two terminal tabs run:
php -S localhost:8080 -t web web/index.php
sass -w web/stylesheets/main.scss
Alternatively, if copy .env.example to .env you can start using foreman.
foreman start -f Procfile_dev
From here you should be able to visit http://localhost:8080/ and see the site.
Hopefully the setup should just be a matter of dropping the repo on a server and pointing your chosen configuration to the /web/index.php file.
You may also want to precomile the CSS with
sass web/stylesheets/main.scss --style compressed > web/stylesheets/main.css