If your Apple keyboard is full-size with numeric keypad, the second Opt/Alt
key may work; some older Windows systems (7, XP, etc) could use certain
Apple USB wired keyboards. For a time, some third party free apps were
available to help in that regard; but no longer, it would seem...
Most questions regarding Windows and Mac involve BootCamp to run an
installation of Windows in the Mac. Then, there are easier methods to use
the 'other keyboard' because, expected hardware compatibility exists.
Not sure if your example of Apple keyboard may simply be defective or if
the issue remains with non-compatibility of hardware in this instance.
Did you look to see if there may be a niche of hope contained in the two
articles concerning PC keyboard with Mac (MS Support) or the Apple
Support article about using Windows keyboard in BootCamp? Due to how
the BootCamp helps Windows be compatible ~ that's why this is doubtful.
Many of the keys that you'd see on a PC have equivalent keys on an Apple keyboard
...in Windows. If your keyboard works when ...
//support.apple.com/en-us/HT202676
{Microsoft provides a keyboard mapping article that describes using a Windows
keyboard with OS X. Rather limited prospects when using Mac keyboard w/ PC.}
So you may have to visit a second-hand store and score a cheap PC clone keyboard.
Or new cheap clone keyboard, depending on your location & circumstances.
Good luck in any event...! 🙂