- business: we sell nutritional supplements; a regular customer buys once at least every 90 days if he consumes the products as indicated

- Zoho Invoice: used to make the invoices and manage receivables

- Zoho CRM: used for recording customer contacts, mailings and establish rules

- both are integrated and I can see invoices in Zoho CRM and contacts / accounts created in any of both systems is synchronized

Required data in CRM:

- date of last invoice

- sales amount for the last x days

Objective: identify "inactive" customers and categorise customer in different classes

Although I can see the individual invoices and the overall sales in CRM in the form of a widget, I cannot extract or filter by it.

QUESTION: 

- What is the best way to achieve the above?

- If webhooks from Zoho Invoice to Zoho CRM, how should I set them up?