The map is not visible.

C:\Program Files (x86)\Nival Interactive\Heroes of Might and Magic V - Tribes of the East\Maps

Is that where you're trying to find it? (I'm asking because there's another Maps folder that's empty. Some people were trying to find something in that one.)

It shouldn't have become a hidden file after creation, but you can check that as well. Does the game create the map normally?