I can`t create a new account.

I can`t create a new account.

This Domain is not supported or is already registered with Zoho.

I am creating a new account in zohomail with this domain computar.co but will not let me, I can only see this Domain is not supported or is already registered With Zoho, if they are created, I need to know what the mail administrator to try to reset the password. I need urgent help please.