Each Seller can create new Amazon Product using M2E Pro in case there is no such Product found in Amazon Catalog. To do that it is necessary to:
Detailed information about Description Policy settings you can find here.
Detailed information about New ASIN/ISBN Creation you can find here.
As you know, to create new Amazon Products it necessary to provide UPC/EAN code, but there are an exceptions such as hand-made products, etc. These exceptions means creation of new Amazon Products without UPC/EAN values. However, Sellers must receive/have an approval from Amazon to create such Products.
In case you have approvals you should select one of the Product ID Override options in Description Policy settings:
Once you select a Product ID Override option, you are able to select None value for UPC/EAN.
If you sell Products without UPC/EAN, then while you are adding them into the Listing, ASIN/ISBN can be not found automatically for some of your Products.
Do not worry, you should just press Continue button at the top of this page and move forward.
Press Yes in an opened pop-up to create New ASIN/ISBN.
Then you will be redirected on a step where you should prepare your Product for creation of new Amazon Product. Select a Description Policy with Product ID Override option provided and press Continue.
Amazon Product will be automatically created at the moment of Listing of the Product without UPC/EAN.
The further management of Products without UPC/EAN is the same as for other Products.