Wolff works with composer. In order to use it for the first time you must have Composer installed in your machine, or you can download one of the bundles.
You can see how to install Composer in the official page.
Clone/download the Wolff repository and run the following command in your Wolff folder:
composer install
This will download the rest of the required files and then you will be done :)
The other way to install Wolff is through Packagist: open your terminal, move to the folder where you want Wolff to be installed and run the following command:
composer create-project usbac/Wolff
This will download the whole project with everything required to run.
If you have any problem during the installation, just remember to clear the Composer cache using: composer clear-cache.
You can download the bundles ready to be used which don't require composer.
The bundles can be downloaded in the Wolff releases page.