To integrate with an Amazon order source, your account with Amazon must first be eligible for Amazon Marketplace Web Service. Per Amazon, "To be eligible to use MWS, sellers must have at least one of the following: a non-individual Selling on Amazon account, an Amazon WebStore account, an Amazon Product Ads account, an Amazon Payments account, an Amazon Fresh account, or an Amazon Prime Now account. Sellers with only individual Selling on Amazon accounts are not eligible to register for or use MWS. If you are an individual seller and would like to use MWS, you can become eligible to register for MWS by upgrading to a Professional seller account from the Amazon Services Selling on Amazon page."
Once you have confirmed your Amazon account as eligible for Amazon Marketplace Web Service, just contact the Amplifier Client Service team to set up integration. Our team will take care of the rest.