It's not possible to have file upload in asset metadata schema without customization. Nevertheless this seems to be incorrect usage of metadata schema, it has not been designed for file upload.
Thanks for the inputs. But the requirement is to upload few consent forms (related to asset) for authentication from system (Not from DAM). That's the reason I've a thought of customizing schema with fileupload plugins.
Though I have added the plugins in schema, the selected files are not displaying in metadata console.