Cross-Platform Medical Billing App

I need a straightforward medical billing solution that runs smoothly on both Windows 7 desktops and Android phones or tablets. The core of the system is simple: an Admin user must be able to create, view and manage two clear document types—purchase bills and patient billing invoices... (Budget: ₹600 - ₹1500 INR, Jobs: .NET, Android, Desktop Application, Flutter, Kotlin, Mobile App Development, PHP, Software Architecture)