If you just want to display the current ArcGIS Camera position in terms of long and lat, you could check the ArcGIS Location Component that is attached to the ArcGIS Camera gameobject.
You could also get it displayed in the game window by passing those info to 2D UI texts. You should be able to get the lat and long values by requesting the position. (check ArcGISLocationComponent.cs in Assets/ArcGISMapsSDK/SDK/Components/). It will give you the X, Y, and Z values of the ArcGIS Point, depending on the spatial reference.