Ahh, it’s probably using some proprietary features that only exist in Adobe products.

I’m not sure if they still sell it, but Adobe used to have a suite of form tools where the person filling out the form had to use Adobe Acrobat (it used some non-standard PDF form features), and the company collecting the form responses had to use software built on top of Adobe ColdFusion (which costs thousands of dollars per server). They really tried to lock people in to their form ecosystem.