Just an update for anyone else searching for answers:
In the end, I was unable to set up the Authenticator app without a real mobile phone number. I bought a phone and got service and was able to set everything up without issues. Sad that I couldn’t do it without one, but I suppose it WAS time that I joined the Century of the Fruitbat and got mobile.
Setting up the authenticator DID also set up SMS Protect, so now I am doubly protected and have four extra bag slots as well.
Thanks to all of you for your assistance!