might be a basic question for some and apparently highly technical for me. When you have a workflow put together and you've done the validation check and all seems well. How do you test the flow before deploying it? Is it possible to step through the flow to see how it will react?

After a workflow has been saved and validated, you can indeed run it from the ED debugger, which is behind the green triangle button near the center of your ED toolbar. You will be prompted to enter all of the same starting values as inputs the workflow expects.

Once initialized, you can set break points as needed before clicking the green triangle button again to play it through.

maybe I'm not familiar with what needs to be entered in as values

and a popup about a webrtc call being in progress but nothing happens.

If the workflow uses call intercept events in the start event then it requires WebRTC snapin for debugging. Please install the WebRTC snapin in the same cluster where ED is installed and configure it (follow the instructions in the help. Look for "Debugging a call-intercept WFD").

If the workflow does not use call intercept events then it can be debugged straight away.
Just for your information, the ED help has a section for debugger if you have not seen it yet.