Zoho Books / CRM integration

Zoho Books / CRM integration

Hello! We have the professional version of Books and CRM Plus.

We have synchronized contact, suppliers and products between both. When we create a budget, we always link it to its corresponding opportunity.

If we win the opportunity, we invoice the corresponding budget, but how does CRM integrate the products of this opportunity gained? How do I know what products I have sold to a customer in CRM?
Thank you and I am waiting for the answer