The best way for a beginner is to use a mixamo character and you have a choice to use there animations, or to use unreal animations its very simple to fix the rigging so it looks right.
Only do the following if you want to use Unreals Animations without them looking like ****.
- Make a mixamo character using Fuse.
- Export it to the auto rigger then export it to your desktop.
- Export the unreal Mannequin from the editor.
- Open up your Mannequin character in a modeling program i use 3Ds Max.
- Copy the weights of the model delete the bone/skeleton and skin modifier.
- Import the Mannequin into the same file.
- Heght match your model to the Mannequins then delete the Mannequins mesh .
- Rebuild the skin add back the bones.
- Copy back over the copied weight data.
- Export and Import into Unreal.