Hi,
I tested the code in one of the phaser examples (Phaser 3 Examples) creating an img element with the url of the arrow png file. The code worked correctly.
In your case, as the image is hosted on an external server, it will have a cross-origin policy that prevents access to images via javascript from outside. My knowledge of CORS is very limited, so I hope another forum member can help you with this.
Good luck!