Anytime that pop-up screen appears asking for credentials for the Crystal runtime engine, it means that proper credentials have not been already set. That is not a pop-up from Report Runner Batch; it's the Crystal runtime engine prompting. This pop-up will only happen during testing with the viewer/test window. There are no pop-ups when a batch is running.
The report you're running requires different credentials (ID/password), and it has not being provided. That's why the Crystal runtime engine is prompting you.
If the report works after entering the credentials, you need to manually set those same credentials in the job edit window or via the global ID/password.
If your report requires DIFFERENT IDs and passwords for different data connections, you'll need to use the 4th login option (multiple IDs and passwords). This creates a middle tab in the job edit interface where you can manually set each data connection's ID and password.