An Organization resource is available for Google Workspace and Cloud Identity customers:
Google Workspace: Sign up for Google Workspace.
Cloud Identity: Sign up for Cloud Identity.
Once you have created your Google Workspace or Cloud Identity account and associated it with a domain, your organization resource will be automatically created for you. The resource will be provisioned at different times depending on your account status:
If you are new to Google Cloud and have not created a project yet, the organization resource will be created for you when you log in to the Google Cloud console and accept the terms and conditions.
If you are an existing Google Cloud user, the organization resource will be created for you when you create a new project or billing account. Any projects you created previously will be listed under "No organization", and this is normal. The organization resource will appear and the new project you created will be linked to it automatically.
You will need to move any projects you created under "No organization" into your new organization resource. For instructions on how to move your projects, see Migrating projects into an organization.
Reference https://cloud.google.com/resource-manager/docs/creating-managing-organization?hl=en#acquiring