Build an app or software to be use on smartphone and PC (using whatsUp business)

I manage a small business of production and sale of handicrafts and customization of objects. Customers come to the store, they choose the object to create or customize, I make a cost estimate (price) and then they have to return to collect the chosen object.
I need an application that allows me to acquire customer data, the type of work to be done and to create a receipt (with a kind of qr code) to be sent via whatsup to the customer.
I must then have the possibility to change the status of the order during processing and enter the name of the file of the work done in order to archive it.
At the time of collection, the customer must show me the receipt (qr code) that allows me to identify the work to be delivered.
The system must create a delivery reminder in the calendar with a gantt for the production.
I then need to keep track of the client, the work done and search for them in the future (data base ).
The up must be in italian