How to include Product Id, Item Quantity and Coupon Code in a search string

Hello, I am an ordinary user of IS, not a programmer. I cannot get the following string to work. It results in a red bar quoting “There was an error loading the product that you have requested. Please try again.” does work but clearly both quantity and coupon code string values fail… I want to avoid making a new SKU, the objective is for an offer with a 4 carton threshold to trigger the coupon discount. Please can you help? Many thanks in advance, kind regards, Han.

I am answering my own post… turns out that there is a simple way to do this which is by creating a product bundle