I can't get IOS to make a sound when using a HTML5 Canvas

When I try to place a button on my HTML5 canvas that activates a sound (mp3) it works fine on desktops and android devices but not on my IOS device (Iphone IOS 14.2). 

When I use this code in the first frame:

this.aBtn.addEventListener("click",clicked);
function clicked(){
    createjs.Sound.play("sound");
}

After creating a button with the instance name aBtn and added a file.mp3 to the library with a linkage name sound I don't hear anything on my IOS device (with Safari en firefox) . It does work great on my desktop and android phone.

I tried many different approaches but without success.

(I' using Adobe Animate 21.0)

Can somebody point me toward a solution?  Tnx in adv!