I should have read the description on the assets

Licensed for use only with UE4 based products. Includes the character model, animations and skins

Don't know about other assets none Unreal made assets though

I should have read the description on the assets

Licensed for use only with UE4 based products. Includes the character model, animations and skins

Other assets that Unreal didn't make themselves are fine to use in other engines as far I have found. If you want to be sure read the description and the license that comes with the asset.