Can't use the "firebase" global word in CLI in Windows - node.js

Question

I'm trying to install the Firebase CLI in windows but for some reason it won't allow me to use the "firebase" command anywhere unless I'm in the path C:/Program Files/nodejs. It works fine when I'm in that path, but the whole point of using the command npm install -g firebase-tools is to allow the keyword "firebase" to be globally accessible. So what am I doing wrong? The Firebase docs don't help at all.
The error I'm getting is:
C:\Program Files>firebase -V
C:\Users\David\AppData\Roaming\npm\node_modules\firebase-tools\node_modules\google-auto-auth\index.js:10
class Auth {
^^^^^
SyntaxError: Unexpected reserved word
at exports.runInThisContext (vm.js:73:16)
at Module._compile (module.js:443:25)
at Object.Module._extensions..js (module.js:478:10)
at Module.load (module.js:355:32)
at Function.Module._load (module.js:310:12)
at Module.require (module.js:365:17)
at require (module.js:384:17)
at Object.<anonymous> (C:\Users\David\AppData\Roaming\npm\node_modules\firebase-tools\lib\requireAuth.js:6:16)
at Module._compile (module.js:460:26)
at Object.Module._extensions..js (module.js:478:10)
If i'm in C:/Program Files/nodejs then it works fine:
C:\Program Files\nodejs>firebase -V
3.11.0