Hmmm…I believe Ue4 will only import an animation that already has a skeletal asset with the same bone hierarchy in the engine. Ue4 will however create a new skeletal asset when importing a skeletal mesh, in a bind pose. I come from unity as well, and Ue4’s animation system is a bit more complicated and less user friendly, but is more advanced if you know how to use it. Unlike unity’s mecanim retargeting system, Ue4’s re-targeting features are primarily used for sharing animation data between skeletal meshes already inside the editor. A way around this might be, create a skeletal mesh with the fbx file, just to allow the engine to create a skeletal mesh asset with a skeleton, then try and import the animations. Without the skeleton asset, the engine doesn’t know what to do with pure animation data unfortunately. (or you could just re target the animation in motion-builder instead). Ue4 was mainly targeted toward devs who have teams and create most of their stuff in house (this is changing a bit now), while unity is a very indie friendly engine, and is targeted toward people who don’t want to do all of the work (not saying everyone :D).