Want to switch but have a problem

So I’d like to switch but here’s an issue, my college has this thing called Duo where you need to use your phone (from what I know) to enter in a passkey from your laptop to login to websites for the college I go to. For example just stuff to view classes and assignments, billing, events, the whole 9 yards. Should I keep a dummy touchscreen phone on me for the app or what should I do?