In addition to Rui's question, is NVDA actually running when you do this?
I've received this error on a couple of occasions where I double-clicked on an NVDA add-on file when I didn't have NVDA running.
I realize that this is not likely to be your situation, but because it is within the realm of possibility, I had to ask.
Brian - Windows 10, 64-Bit, Version 21H1, Build 19043
The difference between a top-flight creative man and the hack is his ability to express powerful meanings indirectly.
~ Vance Packard