This video shows a quick and easy approach to copying an animation from the Unreal Engine Mannequin to Metehuman body animations.
Note, that this quick and easy approach works specifically for UE Mannequin animations and is likely to NOT work for animations from other sources such as Mixamo or even Paragon characters.
There is a complete Unreal Documentation page available that describes a detailed process for retargeting animations in general, and that process would be needed for any source that is not the standard Mannequin skeletal mesh. The full documentation page for that process is here: