Click Here for a guide to creating a BigCommerce API account, and getting those credentials.

NOTE: For the “OAuth Scopes” portion of the account creation outlined in the link above, you need to set “Orders” To Modify and “Products” to Read-Only. All other options can be set to none. Also note that step 2 gives you the API Path that you need.

After completing the user creation you will get the Token and ID that are required.