I was forced to fill out an XFA form (that was pretending to be a PDF) from the Canadian government and the experience left me feeling completely subjugated. The lengths that Adobe go to to make sure that you have the most frustrating experience possible is unbelieveable. Searching for alternatives or help leads you to either: be forced to buy their premium software (or a licensed equivalent) or subscribe for Adobe’s online tools. Why is this propriety format allowed in government forms? What is so fantastic/irreplaceable about this format?
Adobe does sell licences for other companies to use the XFA format but even the software you linked has a free reader that pushes you to the paid full version. Also not FOSS.