Once you have located the map file within the files app, press on the space directly above the name of the map file.  

A drop down menu displays the option to Share.  Tap on Share.  A row of icons display, one of which should be CarryMap.  If not, scroll the row of to the left and tap on more.  An Apps screen opens and you should see the CarryMap icon.  In either case, if the CarryMap app icon is not shown, it hasn't been download to your device.

Tap on the CarryMap app icon, and one of two things will happen:  A pop up tells you the file was saved to the Home directory, Do you want to open this file?  Tap on yes.  Or, the window will pop up showing the file being downloaded (from your iCloud folder) and when finished it will ask if you want to open the file.

The Password needed to open the Mobile Map is found below the Download link in the Order detail in your MyAccount in our store.