No problems with the mock server, however the production server is giving me the following message:

"XMLHttpRequest cannot load https://frc-api.firstinspires.org/v2.0/2016/matches/WEEK0. Response for preflight has 
invalid HTTP status code 405."

Notes: 
I'm using the Chrome extension "Allow-Control-Allow-Origin" to enable CORS
I receive the same message regardless of whether file is open in my browser or hosted on AWS.
Error is the same with or without the commented headers below.

Code: (JavaScript)
    function sendRequest(){
      var username = document.getElementById('Username').value;
      var authorizationKey = document.getElementById('AuthorizationKey').value;
      var key = btoa(username + ":" + authorizationKey);
      var request = new XMLHttpRequest();
      var url = "https://frc-api.firstinspires.org/v2.0/2016/matches/WEEK0";
      request.open('GET', url);
      request.setRequestHeader('Accept', 'application/json');
      request.setRequestHeader('Authorization', 'Basic ' + key);
      // request.setRequestHeader('Access-Control-Allow-Origin', '*');
      // request.setRequestHeader('Access-Control-Allow-Headers', 'Content-Type');
      // request.setRequestHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
      request.onreadystatechange = function () {
        if (this.readyState === 4) {
          var myArr = JSON.parse(this.responseText);
          console.log('Status:', this.status);
          console.log('Headers:', this.getAllResponseHeaders());
          console.log('Body:', this.responseText);
        }
      }
      request.send();

Question:
What am I doing wrong?