We need the secret totp key that is provided by kite when you enable the TOTP
If you have already enabled TOTP, then you should have this key. Most likely you would have entered in TOTP based apps like Google Authenticator. In case you do not have the key, then you can disable TOTP and re-enable it.
If you do not have TOTP enabled but you wish to use it. Here is a guide from Zerodha on How to enable TOTP?
Important: Remember to copy the key that is generated during this step (click on Can’t scan? Copy the key link button which can be seen in the image below) . This key will not be visible once your TOTP is enabled.
Note: Only once you have enabled TOTP, then proceed with next steps.