Newest iTunes doesn't recognize iPhone 6s

I have an iPhone 6s that I want to reset since we don't know the passcode. I'm using Windows 10, but I can get access to a Mac if that would help. The iPhone connects successfully to the iTunes version linked in this reset article , but it immediately tells me to update to the latest iTunes if I want to update or restore the phone. However, the newest version of iTunes downloaded from the Microsoft Store doesn't connect to this phone at all, and a message pops up that the USB device isn't recognized. I don't get the Erase iPhone shown on Tom's guide here, so the phone must have a slightly older iOS installed. I've found paid software online that alleged unlocks iPhones but I'm not sure if they're reliable, malware, etc. I have the .ipsw file that I can use to restore the phone but not sure what I can do with it. Any thoughts on how to resolve this situation?