The start modus had been selected during the setup process. If you have chosen the option Start automatically all runnables will be started in the right order.
Runnables can also be started and stopped independently, but most runnables will not work on their own. You must start all needed runnables in the right order.
If you run ARIS on a laptop (8 GB) for demonstration purposes you might want to stop runnables you do not need to ensure more memory for the system.