How can I edit the signup/Signin page for Zoho Creator - Customer Portal

How can I edit the signup/Signin page for Zoho Creator - Customer Portal

I see an option to put header.

But, I am not able to update the text on the Signin/Signup page.

e.g. I have a restricted portal (dg.culytics.com) and want to update the message, asking people to get on the wait list.

Any ideas.