Hi raquelfrometaur
The Half-Fare travelcard for one month is a product of Swiss Travel System and has nothing to do with the Swiss Pass and the customer number.
You bought your Half-Fare travelcard in paper form, not as an e-ticket, so it is not possible to import it into the sbb mobile app or your mobile phone
You can buy tickets at half price with the sbb Mobile App if you add the reduction manually. However, you must show the Half-Fare Card in paper form during the inspection on the train.
Have a nice day. EllenvS.