Need a Xamarin Expert

Client wants an app for iOS and Android where user will be able to: 1. make a photo of invoice/receipt 2. save the photo 3. choose if it is a receipt or invoice (Typ) 4. mark it it was paid or not (Betald) 5. pick date 6. Add additional information once saved in app, invoice/receipt should be saved in fortnox accounting system: [login to view URL] [login to view URL] so the app itself should work like in the video [login to view URL] but instead of Visma it should be integrated with Fortnox.