After you installed and enabled the "File Attachments" add-on, it becomes possible to add and maintain attachments via the "Attachments" tab of a product details page in the store's Admin area.
To attach a file to a product:
In your store's product list (Catalog -> Products), locate a product for which you need to add an attachment and open its details.
In the "Attachments" tab, click the "Add file" button:
Select the file source. You can upload files from your local computer, your local server, or via an external URL.
Upload a file following the steps provided on the screen. The file will be added to the product attachments list:
Adjust the attachment settings as you require.
For example, add more than one attachment for a single product. Use the "Add file" button for this purpose.
Change the title and description of your attachment. Click anywhere within the respective fields, and they will become editable.
Change the attachment file (or the location of the file). Then, use the […] icon to access the respective menu.
Delete the attachment using the "Trash" icon.
Use the "Download" ("down arrow") icon to download the attachment file.
Use the "Membership" dropdown to specify the membership-based group of customers who should access the file.
Drag-n-drop attachments to sort the display order.
Click "Save changes" to save any changes to the attachment details you have made.
When you clone a downloadable product, the clone product inherits the contents of the product's "Attachments" tab. As a result, you get two products using the same file attachment(s).
If necessary, you can then edit the file attachments for the clone product or keep the original files and their settings if you wish to re-use them. For example, you can replace the files, adjust the "Free/Paid" access settings, adjust the availability of the files to different membership levels, and the like.
For information on product cloning, see the section Cloning Products.