WooCommerce Upload My File

https://wordpress.org/plugins/woocommerce-upload-my-file/

The WooCommerce Upload My File plugin allows customers to upload a file an attach it to an order. Once an Order is processed a button will appear in the order overview page and a file upload screen will appear on order-detail page.

The plugin adds a new side panel on the order detail page to allow shop managers to download the attached files.