Hi Abby,
If you want to see the what roles has been assigned to perticular users then that information is stored in following tables
AGR_USERS
further if you want to see the what objects present in perticular role then that info is stored in following tables.
AGR_1251
Create custom datasource in SAP BI stored in data target and create query on that.
hope it will resolve your issue.
Regards,
Ganesh Bothe