How can I extend Mac + keyboard + mouse to a PC through WiFi local network?
If I were trying to do what I think you're trying to do I would use Microsoft's Remote Desktop. It's available for macos from the App Store via this link. It's also free (as in zero cost), so you've only a bit of time to lose for trying it. 

I've used it for years, and found it works quite well for my purposes. I've tried other methods, but for connecting to a Windows host, they always feel "clunky" in comparison.