Can accessing protected customer data in a developed app be resolved?

[paul_ng_hkg]

My partner has provided me the access to a private developed app. This app provided me the right to access customer information, order information etc. However, when I get the order information through REST API, some personal data like the customer name, receiver address, receiver phone number cannot be shown in the order JSON. Besides that, even I get the customer data through API, above data still not available. Seems like it is being hidden, is it related to the protected customer data? Can I solve it?