Detailed information on Workflow

In this blog post Nextcloud Flow makes it easy to automate action and workflows it talks about Flow being a singular Nextcloud App. All I can find are 6 separate apps that are under a “Flow” umbrella. Each of these apps seem to have their own Github page with limited README’s and there doesn’t seem to be any continuity between them. Is there a consolidated location with all the information on Flow and how to use it?

Ultimately I’m trying to automate an email message going out when a file is uploaded to a folder but I have no idea how to go about doing so and I am having a hard time find any documentation on Workflows.

Any help would be greatly appreciated.