1. go to mixamo (need adobe account)
2. choose character
3. chose animation (idle)
4. select export fbx to unreal engine
5. rename it mutant_idle.fbx or the way you like
6. launch unreal engine, and your project
7. create a folder at the root of your characters
8. import from download
9. in import fbx option, select the box animation
10. in import fbx option, select the box materials
11. import in your folder
12. drag and drop the animated character into unreal engine editor viewport interface
13. play to test
14. if ok, file > save > save the new content
ref : https://www.youtube.com/watch?v=SzdxKwwuCeE&feature=youtu.be