Zoho Books mark invoice as paid

How do I post sales orders from BigCommerce to Zoho Books as PAID?

This can be done through the settings in the app dashboard. Every sales order in BigCommerce creates an invoice in Zoho Books. The invoice state can be set to 'Draft' or as 'Paid' depending on your preference. You can set or switch this preference by going to the app dashboard and switching your preference:

Mark Invoice as PAID