It sounds like you have run the change-master-password command on the
domain, or created the domain with a master password. Also, it sounds
like you did not use the --savemasterpassword option.
With this configuration, the start-cluster command cannot be used (as
indicated in the error message).
To start each instance, you must login to the server that hosts that
instance and run the start-local-instance command. That command will
prompt for the master password, and the instance will be started after
you enter it.
Note that this method of running a cluster provides the utmost in
protection of the master password, as it is never transmitted over the
network (unless you login to the server over a network, in which case,
the master password goes over the network when you enter it into the
start-local-instance commands).
If you don't need this level of protection, then use the
--savemasterpassword option, or don't set the master password. Then the
start-cluster command will work.
Tom