Thank You! I am curious as to how you got it to work but it's up to you if you want to explain or not. Thanks for your support!
Viewing post in Unity Sex Animation: Rough Pack comments
No problem! First of all, I only used unity package (I checked "FBX" and "ALT FBX" but they need additional modifications for importing to unreal engine, which I'm not good at). Secondly, I used a paid plugin called "UMotion" in unity, which can convert *.anim files with a skeletal mesh container to a fbx file. This fbx file can be imported into unreal engine with a model. Thirdly, UE5.4 can easily auto retarget this fbx file to any standard skeleton mesh in unreal engine.