If you use cmtool outside of a job, you must invoke the cmtool login command to sign in to the server. After logging in, cmtool saves information about the login session for use in future cmtool invocations. If you run cmtool as part of a CloudBees Build Acceleration job, you do not need to lsign in because --cmtool uses the login session (and credentials) for that job.
To sign in to cmtool:
cmtool login <username> <password>
To specify a session file, use the --sessionFile=<fileName> option, so you can use the same session for subsequent cmtool invocations.