The Delivery & Return section in the theme is used to display the content of the delivery and return policy page on product pages.
Go to Shopify Admin → Content → Pages → Add page.
In the Visibility section, make sure to select Visible (if set to “Hidden,” the page won’t appear on your website).
Please see the video:
Add the content to Product page
Go to Product page > Main product > Group product > Extra link > add Delivery & Return block.