Use the Enter Data Source Credentials dialog box to provide your credentials so that you can retrieve data from the data source.
Type the user name to log on to the data source.
Type the password to log on to the data source.
Data Connections, Data Sources, and Connection Strings in Report Builder
Data Source Properties Dialog Box, General (Report Builder)
Specify Credentials in Report Builder
Report Builder Help for Dialog Boxes, Panes, and Wizards