Troubleshooting Cloudbreak on GCP
Google Cloud create cluster fails with permissions related error
In order to launch clusters on GCP via Cloudbreak, you must have a Service Account that Cloudbreak can use to create resources. In addition, you must also have a P12 key associated with that account.
Usually, a user with an "Owner" role can assign roles to new and existing service accounts from IAM & Admin > IAM in the Google Cloud console. If you are using your own account, you should be able to perform this step, but if you are using a corporate account, you will likely have to contact your Google Cloud admin.
The roles for the service account are described in Service account.