In order to get the VAT number for B2B orders, you need to enable a specific setting in your Amazon seller account: "Buyer tax identifiers". This article explains how you can do this.
In your Amazon seller central you can go to the top left menu > Orders > Order reports
On this page, you will find the option "Add or remove order report columns"
Here you can turn on the Buyer tax identifier setting.
What will this do?
With this setting turned on, we will be able to receive the VAT number for business orders and include it in the order data for Channable API, Lightspeed, Magento, and Prestashop.