For anyone who isn't sure how this 2FA works, here is my understanding:
When you sign-up for 2FA, a random seed code is generated by this forum and shared to your chosen authenticator app, via a QR code scan or manual entry. Thereafter, when you want to login, the authenticator app will generate a one-time-code based on that seed and the current time, using the math described in
RFC 6238. The forum verifies the one-time-code using your seed and the current time.
You can use any authenticator app that supports RFC 6238. I already used the microsoft authenticator app for work stuff and found it works fine with 2FA on this forum. There are other options, such as Google Authenticator or Authy.
When you setup 2FA, you're given a 'backup code' that you can use to gain access if, say, you lose your phone. If that fails, contact the sys admins through email.
I was unsure at first, but now recommend it, it's super easy!