The web2 site will run happily under the PHP development server, but you'll need to have a Redis server running on localhost:6379. You'll also need to configure a suitable Joind.in API; you could use the live Joind.in API or if you're developing against a local version, reference it in config/config.php. Note that the API will also run under the built-in webserver, but will need to be on a different listening port.
To run the site on http://localhost:8080/, do the following:
cd web
php -S localhost:8080 index.php
You can also use the Symfony Local Web Server. From the root directory:
symfony server:start -d
symfony open:local