Now that you successfully have setup your method(s) for receiving your second factor, you can now enable this feature in your users’ accounts. This setup must be done per user and is unavailable in the group setting.
Next to that user, click Edit. (pencil icon)
Use Short Message: This will enable the SMS text message option.
You will need to enable this first in order to select the SMS template and enter the users phone number (Mobile device capable of receiving a text message) then you may choose user discretion as noted above.