Oh yea, the heater needs to be connected to the controller.
What I was pointing out in the drug store heating pads was that they usually have some sort of switch on the line to turn them on and off. You want one where there is a physical switch to turn on so that when the controller applies power the thing gets warm. If it has one of those electronic switches, that needs to be pressed to turn on, then it won't actually turn on when the controller calls for heat. Heating pads made for people also turn off after 2 hours of continuous use, but in practice that hasn't been a real issue for me in my basement. It could pose a problem for someone trying to maintain mid-60's in an unheatd, detached garage in winter.