Shuld I ask for CMS&Cpanel login info on checkout for web security service?

Am offering website security service and I need this questions but am afraid that customers will abandon cart. And am not even sure that everyone has CMS and Cpanel...
Should I just ask them for their login info via email after purchase?
Is there any other way?

You'd better ask by email.
Mostly no one shall enter their details into a form because it is really not secure.

Hopefully using an SSL secured website