Can't signup for free plan for Support

Can't signup for free plan for Support

I have an Zoho account - created when I signed up for Zoho CRM.    If I'm logged in and goto  https://support.zoho.com/ then I'm redirected to a page to " Sign Up for  Enterprise Plan".  I don't want Enterprise plan, I want Free plan.   If I log out and then go to above url, I'm redirected to  https://www.zoho.com/support/ .  In the top menu, I click Pricing & Signup. I click SIGN UP NOW button under the FREE plan section.  When I enter my info, it complains that  " This User Name is not available"

How can I use the Free plan for Zoho Support?