Winning a deal is not the end of the work. The customer still needs a quotation, an order, an invoice and a payment, and when that happens in a separate system, the details from the deal have to be typed in again.
ERPNext, the open source ERP from Frappe, connects to Frappe CRM out of the box. Quotations can start from a deal and won deals become customers in ERPNext, while products stay in sync between the two, so sales and accounts work from the same records. Both can run on the same site, or you can connect an ERPNext site you already use.