It's too bad you didn't have this reference handy & bookmarked:
https://groups.google.com/g/video-downloadhelper-q-and-a/c/BzPLK2YyL-s
There's a few strings I would have recommended you search for in there.
First, I would have had you search on "problem report" in there. That brings up 2 links
which you should click. That would be good reading. That would show you how to post a
proper problem report. VDH may or may not work on your site but nobody can help you
determine that with certainty unless you post a proper problem report.
Next, I would have had you search on "philosophy" in there. That brings up another link
you should click. It discusses what the VDH license does & does not do. Specifically,
it explains how getting a license is about 99.99% certain to make utterly no difference
to how VDH works or fails on any given site.
Next, I might suggest you click the very first link in there. That takes you to a
tutorial on how to use VDH. Perhaps you were already doing things right & the tutorial
would turn out to be no real help. Or perhaps it might help. You don't know until you
look at it.
But you are certainly entitled to get a refund for your license. It's just too bad you
couldn't have gotten help sooner.