Actually, the discount is passed through the Totals Collection as shown below.
The API documentation don’t mention it but I got this data for an order using a discount…
It is a bit tricky at the first place because the data needs to be properly extracted from the Webflow call. I had to use 2 “set multiple variable” modules to get data from the “extra” fields and the “checkout” fields.
Here is an example how to set those modules properly:
I pulled this a year ago so I would need some time to understand the concept but basically, you need to tell Integromat to get the piece of data you need within the Extras array by setting there path and parameters to match.