To be able to set up Two-Factor Authentication via SMS, you would need to verify your mobile number.

Click here to see the step-by-step guide on how to verify your mobile number.

Step-by-Step Guide

1. Tap Settings.
2. Tap the box next to Enable 2FA via SMS.
   
3. Enter the Six-Digit Code that was sent to your phone and click on Submit. If you did not receive the code, you can resend the code by clicking I didn’t receive the code.