HSRP Booking anyone? I'm not getting OTP!

I'm trying to book a High Security Registration Plate (HSRP) appointment on the notified website for Zone 1 but I'm not getting the OTP on my mobile phone after entering all details. [Stuck on this screen \(OTP not coming on mobile phone\)](https://preview.redd.it/pom6eat2uc9e1.png?width=614&format=png&auto=webp&s=974e544470246d5a33564eddc7b7aecf2676afe8) I have a TVS Star City+ (2014 model) and not sure of its Bharat Stage emission norms so I'm putting BSIII/BSIV (best guess) -- it's not mentioned on RC. Maybe it's incorrect, that's why no OTP? My number seems to be updated on Vahan portal correctly so that's not the issue. Any direction/suggestions would be greatly appreciated!