Question about animations

Ok, I ran across a site that as free assets. Im sure people here know it. “Mixamo”
My question is, If you just get an animation from the site. Then a mesh.

Can any mesh be used with the animation? The reason I am asking, is. I did get 1 character off there and an animation.
However, when I checked the animation in Unreal. The mesh looked like it had stretched and rubber band arms and legs?

So I went back, and downloaded the animation again, this time with the skin for the character. And it worked fine.

I do not know enough about this stuff. yet. So I would like to know if any animation could be used with a mesh by making some changes to something ?

yes, you need to retarget the skeleton… … mixamo and ue4 have each changed a bit, but you will get the general idea