If you are seeing "This product has been deleted in Shopify" and "You need to map products" it means that the product the customer purchased is not synced to DSers. You will need to map the product that was purchased, to one of your products in DSers. This help guide from DSers might help.
If this doesn't help, I recommend reaching out to their support team for assistance. Their app is a third party app, thus they will be able to answer your questions directly.
In the meantime, I would love to take a look at your store! When you have a moment please provide your URL and I can provide additional feedback.
Skye | Social Care @ Shopify - Was my reply helpful? Click Like to let me know! - Was your question answered? Mark it as an Accepted Solution - To learn more visit the Shopify Help Center or the Shopify Blog