Install the librarian-puppet and landrush plugins for Vagrant:
vagrant plugin install vagrant-librarian-puppet
vagrant plugin install landrush
Start and provision the box:
vagrant up
Install the SSL certificate on your guest machine:
sudo security add-trusted-cert -d 'puppet/templates/ssl/denkmal-dev.pem'
The website should now be accessible on your host machine at https://www.denkmal.dev.
The admin interface runs on https://admin.denkmal.dev (login: admin@denkmal.org / admin).