Add model to your scene, appending skull group from .blend file
Note: the model is triangulated, but it shouldn't bother you, because it's not supposed to be deformed (e.g. during animation), so clean topology is not necessary. And if you want the model to be less detailed you can easily apply decimated modificator, which works perfectly fine with such geometry.
Note: example scene uses color management, so model on your own scene without color management may look a bit different
If you have any questions, feel free to contact me!