Root motion fix have working FBX But not working RM

I have a very challenging question I have a moose that has both IP animation and RM that I bought online only thing is for unreal the RM does not works its there but none working this is what the seller told me ( Hello! Unfortunately, to work in UE4, you need to redo the animation of the root movement in the original Blender3D file There is no other way to fix it.) would any one know how to fix? would be very helpful.