Create an Android app to collect payments

The project is to allow the users (employees of a company) to collect payments of invoices already generated. The users will need to used username and password to login in the app. Once logged in, the main screen will be requesting the Invoice Number. In the Menu (hamburguer menu on the top right corner) the user will have three options: Collect Payment, Consult Payments, and Provide Payments. With the first option (it's the main screen) the user will be asked for an invoice number, once he provide the invoice number, the backend system will provide the information of the owner of the invoice he is going to get paid and all the invoices that that person needs to pay to the company. So, the app will show the invoice owner information so the user can confirm that the invoice entered is correct. After that, he will see the list of invoices that have some debt. The user could select any of it to go to the detail page and select between which due date he want to pay (dependending on the due date it's the amount to pay) Although, the app needs to suggest the next one, the user could select another date (because he could be paying with a future check or some customer can pay after the due date) Or he can input other amount. Once he complete this for all the invoices he want to pay (could be one or more than one, but could not be all the invoices, the user needs to seelct which wants he are collecting), the user needs to input the form of payments and the amount of each (check or cash). For check the app will request the check number and the bank. Each invoice will have an status, green, yellow or red, this depends on the amount of days that the invoice was due (if it is not due, the status will be green, but if the user is trying to collect a payment 2 days after the due date, it will be yellow or when it is more than 5 it will be red. This will apply too when the user is collecting a payment that is between the first and second due date, but the user select to pay with the first due date amount. Once all the form of payments are done, the user can confirm the collection and he will see the confirmation page with the detail of the receipt. The second option, Consult payments, the user input an invoice number an he will see all the invoices that the owner of the invoice has. Clicking on any invoice, he will see the receipt. The third option is to Provide Payments, this option is used when the user is in the headquarters and he need to justify all the payments he's done. The app will show all the invoices that were not provided yet. The user can see the summary information of the whole justification. Clickin on an invoice he will see the detail of the receipt. Non Functional Requirements: -The app will be connected to a backend using web services (I'll define) -The code needs to be push using git to a bitbucked repo provided by me daily or frequently. -The app is for internal use, so not a great UI is requested. But at least, it needs to be pretty and with good user experience. You must use the good practise of developt and desing for Mobile apps. -The app will be in Spanish but the app should take all the text from a file so I can translate easily. -In case there is no internet connection, the user should be able to use the app normally, so a local database is required and in case the user is traying to submit a payment, if there isn't internet connection, the app should notice that and be ready to sincronized once the smartphone get internet. -Common user funcionality should be there, like forgot password, logout, etc...