Mixamo Animation Import Issue

I attempted to export the SK_Mannequin.FBX from Unreal to Mixamo. Once in Mixamo, I gathered all of the animations I wanted for him and attempted to download them. The download screen did not offer the Unreal FBX, so I chose the generic FBX. Upon importing the files into Unreal I received several errors to include:

Warning: No smoothing group information was found in this FBX scene. Please make sure to enable the ‘export smoothing groups option’

There is no geometry information in mesh

I’ll attach some photos of what I’m doing.

Hi.

Mixamo animations/characters .fbx(not for unreal) do not have root bone in origin(0,0,0) but SK_Mannequin has it, so they are not compatible with each other.

you can download some animations for one of mixamo characters and choose (use in UE4) so it will have root motion,
then in the UE4 you can use animation retargeting(different skeleton)

one more thing.

you must first import a skeletal mesh to unreal then import animations for it so you can select which skeleton those animations belong to