To successfully integrate your BigCommerce store, you must be the Store Owner, or have access to the Store Owner’s account.
The Store Owner is the primary user for your entire BigCommerce account. Unless you've changed it, the Store Owner is the first user account created when you start a new store and is granted all administrative permissions.
If you are not sure if you are the Store Owner, go to Account Settings › Users. The Store Owner's email address will be listed as owner under User Role.
If you don't see Account Settings or Users in the navigation, your user account has not been granted permission to access those areas and are not logged in as the Store Owner.
Changing the Store Owner to a different user:
You must be logged in as the current store owner in order to change the store owner user. Go to Account Settings › Users, click the Action button next to the user you want to assign as store owner, and select Edit. In the User Role dropdown, select Store Owner.