Just to chime in a bit on this, but URl avatars sometimes have some funky business with broken links and whatnot. That's why I assume that the site was coded with the age old method of just uploading an image.

If you don't have a photo editor program as well you can use a few online resources for image cropping and resizing. I use https://resizeimage.net/ and found that it's a real simple and basic alternative that isn't too difficult to use, even on mobile.

Asking a mod is also a great option as well and thanks [@Stormflyx] for helping. I've personally played around with photoshop for years and while I don't necessarily have it on my computer anymore, simple Avatar stuff is a breeze for me if you need a hand.