You may want to put "Service Consumer" in Allowed roles to make this service use basic authentication.
"Service Consumer" role is defined for users that have privilege to run Cloud Application Integration Processes. Any user that has this role (You can check this by going to Administrator > Users > Click on User and see roles assigned to this user) can execute the process. Please make sure to un-check "Run as Anonymous"
Please use the username / password of the Cloud account that has this role when you invoke this service.