Not Working for Me

I want to create a bogo. When the user adds 2 of an item they get 1 of the same item free.

I set it up that at a specific product a customer buys 2 of the product then at specific product a customer gets 1 at 100% discount of the same product when using the assigned coupon code, but in the cart when I add the coupon the discount shows as zero.

I can overcome this by adding another item of the product, so it is actually that the customer needs to add 3 of the product to get the discount.

How can I make it that when the customer add 2 then use the coupon the 3rd is added automatically?

I hope to hear from you soon.

P.S.: A good point to consider is to add a choice if the admin wants to add it automatically or not, also if the item shows as it is now or adding a new item which shows as a discounted product, then the discount also would have a choice to be applied to the item list or coupon.