Question iAmsterdam Card App Address Request - Why?

Hello all: We will want to see many museums and use public transportation frequently so want to get the iAmsterdam card. However, the app is asking for a complete address to proceed. Does anyone know why this is necessary? Is it just for registration purposes, or does it affect how the card is used? Also, has anyone had issues with privacy or data handling with the app? Would appreciate any insights before we proceed.