The plugin applies several “fixes” to the Mixamo assets to integrate them better in Unreal Engine 4 (e.g. to make Marketplace animations work with Mixamo characters, etc.). Applying such animations to a player character/pawn is out of the scope of the plugin. To see an animated skeletal mesh, you must assign a fixed animation to your player pawn or (better) assign it a custom Blueprint Animation that activates and blends the right animation assets depending on the state/action of your pawn. You can find useful info here:
- https://youtu.be/vzGO_xToP78?list=PLZlv_N0_O1gb5sdygbSiEU7hb0eomNLdq (playlist “Blueprint Twin Stick Shooter, v4.8”, videos #16, #17, #18, #20)
- https://docs.unrealengine.com/latest/INT/Gameplay/HowTo/CharacterMovement/Blueprints/index.html
- Animation Blueprints in Unreal Engine | Unreal Engine 5.3 Documentation