UFbxFactory ignores any binary buffers you pass to it for no real reason.
Instead it loads file specified in its CurrentFileName field. So, set “yourFbxFactory->CurrentFilename” to the filepath you want to load and pass nullptr (you’ll have to create temporary vairable - “const uint8 *tmp = 0;”) as a buffer to FactoryCreateBinary method.
You also cannot set default import settings, you’ll have to enable import dialogue (yourFbxFactory->EnableShowOption()) and let the user select them.
If you’re loading multiple meshes, reuse the factory. That way the user will be able to utilize “import all” button.
You don’t really need to go that route, you can use UFbxFactory instead.