From discussing with the vendor directly, it sounds like the device is intended for 2014 Elantra GT's (couldn't find anything that explicitly listed the GT model as supported though), but Dorman support did say it's supposed to work on this car

Dorman Support said I had the right model for our car, and if it failed it was a sign of a faulty unit and we should seek a replacement from the seller.(Side note - The seller was super easy to work with

Dorman support suggested it was defective, returned to Amazon seller (partshawk) and got refund (I paid postage).

After 2 failed attempts, I called Dorman support to explain what I was up against and that I only had 1 try left

We programs 2 fobs for his car and everything works as it should.