Not so long time ago Octane Renderer became free for personal and commercial use in UE4 - https://home.otoy.com/render/octane-render/demo/#prime
I just tested it, but unfortunately, CC3 characters (And MetaHumans as well) don't have any texture on the final render. It might be Octane's issue, but I think the Reallusion team should look into it anyway because it's a great opportunity to attract more attention to the CC3 product and improve the product overall.