Quik99oli is correct. Starting in the early 2010s (with the 4th gens), if not earlier, FCA took this feature away. Only way to do it on the 4th gens was with an aftermarket programmer, module, or app, and even then it only worked on earlier model years, if I recall correctly.
The story (rumor) I've heard repeated over and over goes something like this:
After one of many hurricanes hit down south, some folks had accidentally (or purposely) lowered their windows using the key fob, forgot they were down or claimed they were lowered by accident, and the hurricane came through and destroyed their car interiors. They then hired lawyers to go after FCA because it was the feature's fault, not their fault. (Because its always someone else's fault anymore.) As a result, FCA, presumably at their lawyers' request, removed the feature.
Regardless of why, its not currently available on the Rams as far as I know.