The completed CMS tutorial application created during https://book.cakephp.org/3.0/en/tutorials-and-examples/cms/installation.html

1. Download Composer or update composer self-update.
2. Download this source code.
3. Install dependencies with composer

composer install

Update the 'Datasources' configuration in config/app.php for your local database. You'll also need to create a database and run the SQL located in the tutorial.