Create a fee structure, assign it to a class, and record a payment with a printable receipt.
Go to Fees → Structures and add a structure with its instalments. Assign it to a class to create a fee row for every active student.

Go to Fees → Payments and record an offline payment against a student. Overdue amounts refresh automatically on the dashboard.
Online payments (Razorpay) appear on the parent portal once your school connects its own payment keys under Settings → Schools.
Click any payment and choose Print / save as PDF for an A4 receipt with your school header.