In order to deploy via Cloud Build located in project MANAGEMENT to CloudFunction located in project STAGING,PROD you will need:

1. In project MANAGEMENT, get email of account for xxxxxxxx@cloudbuild.gserviceaccount.com

2. In project STAGING and PROD add this account as princial into IAM and add Roles:

   IAM Role Name	IAM Role Permission
   Cloud Functions Developer	roles/cloudfunctions.developer
   Service Account User	roles/iam.serviceAccountUser