I want to make a custom button in the CRM. I want the button to take me to that specific customers invoices in zoho books so I can then take a credit card payment (since CRM does not do that). 

So if I am in Sally Maes contact in CRM I want the custom payment button to bring me to Sally Maes invoices overview in books. If it cant bring me to her invoices then I would it to at lease bring me to her customer in books.