Scenario
Customers are eligible for a 100% discount on an additional item when they buy at least four of that items.
Solution
By utilizing Item Promotion we can create a promotion for buy 4 get 1 free.
For that Navigate to List> Marketing> Promotions> New (Item Promotion)
Add basic information like “Name” & “Description”
Select the item name or select the Saved Search to specify the Promotional items
In the Item Quantity field select the no of quantity and in the Discount Rate field enter the rate as 100%

Apply this Discount to Cheapest Disounting Item

To specify customers under the audience select Specific Customers and Select the Customer Category or select the Customer after that Save the Promotion.

To Apply this promotion create a Sales Order and when we add the Particular item with quantity 4 automatically the Discount is added. Please refer to the below attached screenshot.
