I uploaded this model so other people don't have to waste an hour printing just to find out that it doesn't fit at all. I tested it as shown in pics.
Works 100% with WMVos's side mount: https://www.printables.com/model/711231-ender-3-v3-ke-filament-spool-side-mount-toolless
Special thanks to WMVos for the side mount it works perfectly - feel free to add my model to your collection/description so people can find it easier.
Thanks to fonzy for the original model.
And lastly thanks to Brian for the idea of using the original mounting lugs.
The author remixed this model.
The main difference from Brian's model is that it actually fits and is oriented correctly.