You might want to also review this post because the one you shared was from 10.2 and this one is from 10.4.

A comment on another post (this one), was posted by a Laserfiche employee in February 2022, and actually refers to that 10.4 post I shared above and says "For every release since Forms 10.4, we have done smoke test with Topaz signature pad integration( following the steps documented at this thread) to make sure it works.)

I don't use this myself (we use Wacom pads, not Topaz), but that post makes it sound like it will work.  But bear in mind, you'll need to be sticking to the Classic Designer, not the New/Modern Designer to make the Javascript work.

Good luck!