The user is first required to Sign Up on the GST Application
'Express GST' Sign up procedure

Step 2 – Create an account on the application, choose a plan that suits your need and register:-

Step 3 : Once Registered, an OTP will be sent on the email id entered for validation. Check your mail inbox (also check spam folder) for the OTP so received and enter the same.
Then, click on “Verify”.