The first step with Footwork is to use the “Detach” function.
So, open an InDesign document that has regular footnotes (“in a single text box”).
Select that text frame, and run Footwork.
In Footwork, click on the “Detach” tab, and click on the “Detach” button to detach the footnotes.
You can now return to the main tab and click on the “Compose” button to layout the the text.
This is all explained in the User Guide that comes with the demo download, in the Quick Start section (on p. 4).