In short - you are on the right track, apart from the locked screen (which is not supported).
For example, background automation could also mean automating a web browser that is minimized → please try Full Text activity in such a scenario and it should work.
Apart from this simple example, background automation using an unattended robot means:
- You launch your process from Orchestrator
- Orchestrator creates and RDP session with your machine and logs-in to your user.
- Robot on that machine is executing the process in the background.
With community edition it is a bit tricky to do, because the robot service is only installed for particular users. This means that realistically the easiest to achieve background automation with community edition would be by having a remote machine that you log into, but then disconnect from. Orchestrator will be able to connect to that active session and run your process unattended (=in the background).
Thus, with all that said - I would first try to automate by trying to automate a minimized window of the application. That is typically a good benchmark if specific application is compatible with the activities set to work in the background. It can be that some applications do not work properly with Simulate Click and Send Windows Message properties, or do not let you extract the text when they are not in focus and visible.