I have a Mini and Air2.  These use the Fly app.  I need to know how to download maps ahead of time for situations where I will not have cell coverage.  I use an Ipad Mini Version 5.  Any help is appreciated.

I am having the same issue. Have you found out how to download the maps ahead of time yet? It is certainly not obvious within the app itself.

Just turn the drone on at home and enter the map screen over your wifi connection of the area you intend to fly. The map will save for when you arrive.