Magento2 Webkul Product File Attribute Module - allow to add your own custom product file type fields.
copy and paste the downloaded folder & file to app/code/Webkul/ProductFileAttribute
php bin/magento setup:upgrade
Run the following commands in terminal-
composer config repositories.product-file-attribute vcs https://github.com/rani-webkul/product-file-attribute.git
composer require webkul/product-file-attribute dev-master
php bin/magento setup:upgrade
now module is properly installed
Follow the blog link https://webkul.com/blog/create-and-manage-product-file-type-attribute-in-magento-2