If the software is able to automatically determine that an eBay listing is the same as a Shopify store product, you'll notice a message on the Publish page
We were able to automatically match 2 of your existing eBay listings to your Shopify products based on title or SKU.
Select Review and link these products
If everything appears to be correct, select the Link products button
If there are products that are not linked to the correct eBay listings, select the Remove button to the right of that product information. Or you may choose to select the check boxes for one or more products and then choose Remove products from list.
If you've chosen to Link products, you'll notice a progress bar indicating that the listings are being converted.
The final step is to Approve Match. Once the match is approved, the listings will follow the sync settings that are enabled.
Once the listings are linked, they may be located under Published products