You don't need much to run the code in this project: just PHP 7 and composer. Run:
composer install
Run the (unit) tests:
vendor/bin/phpunit
If you don't want to install PHP 7 on your machine, you could also run:
vagrant up
This will set up a Vagrant box for development. Afterwards you can run:
vagrant ssh
cd /vagrant
Then run the tests (see above).