Hi,
I'm not sure how you would do media controls for a web based service like Amazon music (or Spotify etc).
The only
shortcuts I've found are for Windows Media Player.
Chrome browser does have a little
control panel that allows you to play / pause & skip media.
The way I play / pause & adjust volume is using my on screen keyboard.
It's a program called
Comfort OSK, I've created a custom KB layout (
here) with media controls that you just place the file in this folder (C:>Program Files>ComfortKeyboard>Keyboards).
This probably isn't the exact answer you were seeking, but it may give some other solutions to your problem.