G2SV is the single-most effective measure you can take to secure your WFU Google account. You sign in with something you know (your password) and something you have (a code sent to your phone, printed backup codes, or a security key).
Guest Accounts will be required to enable G2SV and will need to be linked to one phone number (cell or office number) in order to initially enable. Use these instructions to enable authenticator for multiple users.
Once G2SV is setup on a Guest Account that is accessed by multiple people, each user approved to access that account will need to setup the Google Authenticator app on their mobile device (Android or iOS).
2-Step Verification - Help Articles