Email Service Advice 2022

Advice. I need one email address, preferably Gmail. Two users both have access to the email account. None of them can ever get locked out of the email access. Each user should be able to have two factor authentication ability for the email because two factor is always required in 2022 and beyond. The email service should be free. Advice only. I am not ready to get the new email. Gmail allows only one phone number and that is where the problem arises. The process should be easy to implement for computer novices.