Free products after buying a certain amount

Hello, I don't know if this is possible with opencart out-of-the-box or if I need an extension but I want to sell a certain amount of items, when that amount is reached the buyer gets 1 item for free, so for example somebody buys 4 items, the 5th one is free. If somebody buys 9, the 10th one is free... you get the idea.

Is it possible to do it with Discounts or Reward Points? Or I need an extension?

By the way, all my products will cost the same.

See if your free product is different like you are giving a freebie then you can check this extension:



Extension link: Free gift products based on cart total


And if want to give same product as free when customer buys 4 products which means it is 4 + 1, check this extension:



Extension link: Product combination offers

We have more offer creation module which you check here: More offer creation modules

But we suggested you best ones based on your question.