Today I was a creating Business Process Flow as per my requirement and noticed a Add Flow Step (Preview) when I was trying to Add a Stage.
Just went ahead and explored it. Added a step and configured a flow to trigger. And you know, it gave me a shock :(. I thought the flow would be triggered automatically instead it has shown a button to trigger on the Business Process Flow.
I think, it should get triggered automatically without any user intervention. As this is still in preview, hoping it would be an automatic trigger once it is GA (General Availability).
Hope this helps.