Under the Settings, there is an option to match the products between the platforms using the unique ID. You can select a field from both the platform where you store the unique ID of your Product/item. The system will automatically use that field to map the items.
What if some of your Items are not having any unique key? No problem! We have an option to map those items too as per your need.
This Item mapping page allows us to view all the items, map them & update its mapping too. There is also an option to filter the items here by their mapping status.