You must've forgotten that question, because its in the
application (Question 17). I don't think they ask you, they confirm your option selected- maybe at that point you can say you want an e-certificate and they will send you the email with the instructions?
I would call as soon as possible and ask if they can send you an invitation to create your profile for the e-certificate. Basically you need this -
CIT 0090, call and ask for that specific document. The yellow arrow points to your personal invitation code that you need to setup the profile.