Short Answer - No.
Vizzlo and Xara Cloud are separate systems, and do not share login credentials between them. You can still use the same login service however such as Google or Microsoft.
If you are using a conventional email address and password when signing up to Vizzlo, it's recommended to use a different password for security reasons (you can use the same email address).
Xara won't automatically create you a Vizzlo account when you login to our service.