Unsafe content, JS audio [closed]

I am finalizing a JavaScript, and only one audio is missing when an event occurs. I'm testing the following code:

console.log('sobre audio');
        var a = new Audio("https://mdn.mozillademos.org/files/2587/AudioTest%20%281%29.ogg");
      a.play();

The code above works, but when I change the link to an audio link of my choice it generates the following error in the console (in bold, the link that was replaced):

  

Loading mixed (insecure) content " link " on a secure page [Learn more ] game.php   GET    link

Although it says that it is loading, the content is never loaded, probably because it was alerted as unsafe.

What domain can I upload this file directly so that my browser (Mozilla) recognizes and executes it? Or the problem is not this?