How to enroll Google Authenticator by using Resource Owner Password Endpoint

Hi, I’m using Resource Owner Password Endpoint (/oauth/token) to log the user in my SPA. I also enabled MFA Google Authenticator.

When a user enters their credentials into my login form, the token endpoint response an error that MFA is required. So in this document Authentication API Explorer, I need to send a request to verify OTP code of user from Google Authenticator App.

But the problem is those users is not enrolled to use Google Authenticator before.
How can I get QR Code and show it to allow users enroll?