If you want to schedule or run multiple processes at the same time, then wont be able to do it with the same robot. If Process A is running from 9:00 AM to 11:00 AM and you want to run another Process B within the same time, then you have to may not be able to achieve the same with the same robot. You have to run it within another Robot.
However you can run processes one after another within the same robot. In Large scale implementation there may be the need of multiple process to be executed simulaneously at the same time which can’t be achieve using the same robot. In those cases multiple robots each one of them running an individual process may be needed.
Orchestrator CE provides 2 free robots and its completely free to use without any validity.
Let me know if it helps.