When you deploy for the first time to a production evironment Mendix will popup and give you the choice to get a SMS or configure the Google Authenticator.
Scan the code with your app on your phone and it will be added with your company email adress in the list of codes. Enter 1 for confirmation.
Want to use the authenticator also in your own app: use this connector: https://appstore.home.mendix.com/link/app/2948/Mendix/Google-Authenticator-Connector