Hi,
As far as I know yes, it's the only solution.
There is no demo of this plugin.
What that plugin does is that it will allow you to select a product in the coupon edit interface.
Then, when that coupon is loaded on the checkout, the plugin will automatically add the selected product to the cart and change its price to 0.
So with the settings of the coupons, you can have it auto loaded, and you can have different coupons for different products or categories of products in the cart, etc, and have that free product added together with the coupon.
And similarily, if the coupon is removed from the cart because the situation doesn't match with its restrictions the plugin will automatically remove the free product selected in the coupon.