The Brizy Cloud account included with your Author license is only for you, the owner of the Brizy account. You can use it to do client work and to create landing pages or websites for your clients but there are no tools in place to let you offer the cloud service to your clients.
Brizy Cloud doesn't have a white label feature that can be used as part of your Author license to be shared with your WordPress theme clients.
You'll have access to Brizy Cloud as long as your Author license will be active.