Keyboard Library Not Working Correctly?

I loaded up the example codes for the Keyboard functions, but it seems something's gone very wrong with some aspect. Despite the fact that Keyboard.h is clearly in there, it seems to fail.
I get the message:
'Keyboard' not found. Does your sketch include the line '#include <Keyboard.h>'?
Despite the example code provided to me clearly has it. Is there an update that broke the Keyboard library?
btw, I'm using a Mega 2560 and am forced to do so, so I hope I don't need to switch.

I'm using a Mega 2560

There is your problem.

The keyboard library does not work with the Mega.

See Keyboard - Arduino Reference

Is there anything I can do to substitute? I don't have another option but to use this...

You can, with some effort, program the USB helper chip on the Mega to use the keyboard library. I do not recommend it.

What are you really trying to do? Maybe there is another way.

Well I'm basically making the arduino interact with a python tkinter window. I tried a serial library for python but it was the most problematic thing, so I just stuck with what I knew. Ultimately, it'll turn out to be a skee ball machine...all I need is to have adruino interact with the Tkinter scoreboard reliably.

I know how to set keyboard presses to trigger the Tkinter window, but if there's a reliable and more straightforward way, that would be awesome.

Also I have a week to complete this before I'm forced to scratch it, but I feel like I've gone too far on the Python side to turn back. Plus, my experience with Python is far greater than my experience with Arduino.

Python? That will take a Serial input. No keyboard library required.

Well I tried working with python serial libraries but for some reason they just don't function correctly.
In any case, I dont know how to apply that with TKinter windows as I don't think I can have more than one thread at a time for my project.