Digital download links are only sent when orders are paid - you can also only resend them if the order status is "Paid"
In the event that a digital download URL expires before your customer can access it, you can generate new links via the Order page.
Login to your Dashboard, then navigate to the appropriate Order.
From the Order page, click "Generate new download links".
A pop-up will appear with the option to specify how long you want the new download links to be active before expiring. Choose an option then click "Send email"