Set conditons and let the free gifts role in.
Set your targets
Include all the product ID's you wish to check the cart for.
protected $targets = array( 558, 559, 560, 561 );
Set your quantity
// the required target's quantity needed to earn the free gift. protected $required_qty = 3;
Set the free gift
protected $reward = 562;
You are all set for free gifts.