Easy way is go to the zone > Open up developer tools in HB > Click on Console tab > In top window type Log(Me.MapId); > Click run. The number in the bottom box is the MapId. The If Condition should be <If Condition="Me.MapId == 604">. I use this method for:
Log(Me.MapId);
Log(Me.ZoneId);
Log(Me.SubZoneId);
Log(Me.HearthstoneAreaId);
Log(Me.HearthstoneAreaId == Me.ZoneId);
Log(Me.HearthstoneAreaId == Me.SubZoneId);