If you only want to use the schema of the feature classes and tables in the geodatabase, right-click on the geodatabase you downloaded and, in the Export sub-menu, click on "XML Workspace Document...". In the dialog box check the button "Schema Only" and browse to a location to store an XML file. After that completes, right click on your destination database and, in the Import sub-menu, click on "XML Workspace Document...". Select the XML file you previously created and the geodatabase will have all the same feature classes and tables without the data.