[Commentary here about making sure the license file is either copied to the SCS server or is reachable via HTTP from the SCS server.]
Installing from a file
To install the Swarm license, use: scsctl license add -f {path to license file}
scsctl license add -f castor_license.txt added
Installing from a URL
To install the Swarm license, use: scsctl license add -u {URL of license file}
scsctl license add -u http://license_server/path/to/license/file added
Confirmation
Once added appears after the command as shown below, you are ready with the Swarm license. To visually confirm:
scsctl license show