Widget Unlock for Minimal

Don't understand why this app needed to be purchased and downloaded in order to use another app for a watch face on Wear OS. I can't give any reason to tell anybody here if this is a good app or not, but I'm certainly confused about how it's related to a completely separate app purchase that I made.

I have purchased and installed. Only menu option is "Thank you!". Can't get plug in to work in simple & custom app. Not simple enough, no instructions.

After payment it does not unlock the widget. What's the issue?