Just ask them, they don’t always write why it was rejected, but I never heard of anyone where they wouldn’t have answered it after asking for the reason.
Many of the screenshots on your website look definitely better than the screenshot you posted in the first post of this thread. To me it seems like your character looks quite a bit better in Unity than it does in UE4, so maybe you just don’t know how to create a good material setup for your character in UE4.
But I also have to say, your animations looks really not good. It’s clearly visible that they are not motion captured, and there are many great motion captured animation packs on the UE4 Marketplace. So maybe Epic just rejected your submission because of those animations. Just ask them.