Thanks for contacting us about our product!
We remember default of WooCommerce doesn’t allow upload file.
Can you tell us what plugin you are using now and Test Case to have the issue.
So we can have solution for you.
However if you want a link can download you need to add download attribute like this in the link of Email: https://www.w3schools.com/howto/howto_html_download_link.asp
Hope this helps!