Currently Metahuman Creator supports export via Quixel Bridge where you can choose between exporting UE4 assets and source assets. Currently, source assets can be imported to Maya 2018, 2019 and 2020, and once in Maya you should be able to further export your content in a way that suits your needs, like fbx, obj, etc. Please notice that Maya scene will use custom plugins “RigLogic” and “RbfSolver” in order to run rig itself.
Please refer to licensing model for more details how exported assets can be used.