Please see the composer.json file.
Run composer composer install to load all dependencies.
To test this application you can run it with PHP Built in Web Server
php -S 0.0.0.0:8080 -t public public/index.php
Then access it on web browser http://localhost:8080, it will redirect to documentation page http://localhost:8080/apigility/documentation.
If you want to continue development, you should enable the development mode by rename file config/development.config.php.dist to config/development.config.php. Then modify the controller file (module/Application/src/Application/Controller/IndexController.php) by change this following line
return $this->redirect()->toRoute('zf-apigility/documentation');
to
return $this->redirect()->toRoute('zf-apigility/welcome');