Login into your BigCommerce admin panel.
2) Click on "Advanced Settings" > "API Account" menu. Then click on Create API Account button.
3) Insert ApiDrop in the name field and be sure that all these permissions are correctly set.
Customers: Read Only
Information & Settings: Read Only
Order Transactions: Read Only
4) Press Save button and store carefully the .txt file that BigCommerce is providing you. It contains the store's API connection credentials.
Please note: To connect your BigCommerce store, it must be publish and not "Down for Maintenance"