It is highly recommended to use the Google Authenticator App (or alternative two-step verification token service) to generate the token for your 2FA.
The SMS should only be used if you have accidentally lost or deleted the Google Authenticator app/token.
Please note that the SMS feature can only be sent to a valid Australian phone number.
Can you send to a non Australian Mobile Number?
If you are not in Australia or plan to go overseas, please ensure that your 2FA is set up correctly so you are able to login to your account.