Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I strongly recommend you to connect the ANT first. If the foot pod is wireless / radio / WiFi, then you need the ANT to work.
I suspect you have a defective ANT; That does sometimes happen, disappointing as it is. (I recollect only one such case, but that was how it turned out.)
I think this, because you say you have followed all the instructions in the books, and gotten no result. This indicates a defective wireless link, either in the ANT or in the Garmin FR70... unless you may perhaps have A. a very noisy industrial environment around you, like a machine room or a laundry room, in which radio emissions are abundant, or B. a metal-walled environment in which signal echoes might create 'dead zones'... rare, but it can happen.
I would say, return the Garmin FR70 and ANT as defective promptly, and get either an exchange for working units, or at least a refund. (If they were bought from the same vendor or store, that would be convenient for this process.)
As for why your answer was not prompt: I suspect that many Experts here retire in the evening hours of Eastern U.S. Time for rest and dinner and sleep. I myself happened to be awake and took your case on... or it might have waited until morning (Eastern Time zone) unfortunately.