The Login screen allows the user to select a geodatabase. If you're working with a Mobile application such as Redliner, you'll most likely choose a backdrop database.
Select a database from the pulldown menu, enter a user name and password, and click OK. A password is not required for an Access database.
If you have ArcFM Viewer for ArcGIS Engine installed, values may be added to the pulldown menu using the ArcFM Engine Administrator. See the ArcFM Engine Administrator online help for more information (available with Configuring ArcFM Solution online documentation).