If you logging in the app for the first time and your organisation has enabled 2FA, you need to set up 2FA for the first time. To do so, please check out the following page: How to set up 2-Factor-Authentication using Google Authenticator app?
Once you have setup the 2FA, you can login in the app by verifying your credentials and one time password from the google authenticator app. Follow the steps:
Enter your valid credentials and click ‘Get started’
Open Google Authenticator app
Copy the 6 digits-code from the google authenticator app and paste it in the space provided in the app
Please note: You need to be quick while verifying the 6-digit code from the google authenticator device as the code expires after 30 seconds and you get a new code.
You need to follow the above steps every time you log out of the app