The quickest way to use ACF Builder is to require the autoload.php file (Composer's auto generated vendor/autoload.php or ACF Builder's custom autoload.php file) in your functions.php code. If your theme is set up to use composer, no require is needed.
Create new FieldsBuilder objects to create ACF groups, and setLocation to where you want them to show up in the admin.
Use ACF's built in actions to register the field group config with ACF.
$banner = new StoutLogic\AcfBuilder\FieldsBuilder('banner');
$banner
->addText('title')
->addWysiwyg('content')
->addImage('background_image')
->setLocation('post_type', '==', 'page')
->or('post_type', '==', 'post');
add_action('acf/init', function() use ($banner) {
acf_add_local_field_group($banner->build());
});