Welcome to the forum!
Hhm, you must have installed that extension. I don't seem to have it. Can you give me the link where you downloaded it, so I can test (or someone else can, in case I can't figure out the problem)?
In the dialog in your screenshot, I'm not sure what "Preamble File" means. Do you know?
The only thing I can think offhand, is that you might be getting a result, but it's not showing on your screen. There's a known bug that might be causing the result of the extension to be placed somewhere that you have to scroll to find it. If it's a new blank file, the result might not be very far away. But if it's a file where you've done some work already, it could be hard to find. But you can avoid that bug by creating a new layer, make sure that layer active, and then run the extension.
But if you still don't see any results, please share the link to download it. Or it's possible that someone else might already know the answer for you.
