Hi there,
Are you trying to import those animations onto one of the example characters included with UE4? Like the blue mannequin guy or something? From the error that you mentioned (unable to find Root), it sounds like the hierarchy in the animation that you are trying to import does not match the hierarchy of the skeleton/skeletal mesh that you are attempting to import it onto. In order to import those animations, you’ll need the basic hierarchies of the Skeleton in UE4 and the joints in the animation files themselves to match.
There are plans to eventually support in-editor retargeting between skeletons with different bone names, but you probably shouldn’t expect that functionality for a while.
Good luck!