Hot folders cannot work without any Action Lists or a Preflight Profile. A hot folder must have either a Preflight Profile or at least one Action List before you can successfully activate it. In other words, a hot folder can be valid when it has:
A hot folder can have several Action Lists, but only one Preflight Profile.
To be valid, other requirements need to be met, e.g. a hot folder also needs valid paths to the respective input and output folders. When the hot folder is not valid, the errors to be corrected will be shown at the bottom of the dialog, and in the Summary. See Summary.