Merchants have access to their customer's return shipping label through the RMA details page.
In the Manage Returns section of your Returns Manager dashboard, click on the RMA to navigate to the details page. You should notice that there are two links on the top left corner of the page.
The first link will direct you to the Unified Return Confirmation page. You could send your shopper the link to this page. As shown in the image below, there will be a "Download Shipping Label" button that will allow them to download their shipping label.
Alternatively, you could click the "download" link below the Label cost amount on the RMA details page to download your customers shipping label to send as an attachment in an email to your customer.