I have filed many application and never had this issue of not receiving OTP.
Sometime, if GST server is busy there may be some delay in receiving OTP.
You can request OTP again.
I will advice you to wait for some time, you will get the OTP.
If you do not get OTP even after waiting for at least 2-3 minutes. Click on resend OTP. OTP will be resent.
chatCommentsI waited for good 5 minutes in one of the case. I think there is no time limit for putting OTP. Atleast not at the time of writing this comment. - Pulkit Sharma