I have the Garmin HRM and an ANT+ USB dongle and it works with Zwift on my computer, but not on my iPhone or iPad. The newer iOS devices need an expensive adapter to make them work, lightning to USB, or a lightning to 30 pin and then a 30 pin dongle. So, just get a bluetooth as suggested and be done with it.
Even though I do the same commuter almost every day, I still wear it every time.