The SSH Client Users are used by all applications that play the role of an SSH Client. Specifically Tunneling in Connect Mode.
At the very least, a Password or Key Pair must be configured for a user. The keys for public key authentication can be created elsewhere and uploaded to the device or automatically generated on the device.
If uploading existing Keys, take care to ensure the Private Key will not be compromised in transit. This implies the data is uploaded over some kind of secure private network.
The default Remote Command is '<Default login shell>
'
which tells the SSH Server to execute a remote shell upon connection.
This can be changed to anything the SSH Server on the remote host can execute.