While in the PC edition it is possible to download maps from realms, in the pocket edition not! Some of you might say this is not a bug, but a feature request, but in my opinion this is a very big problem as if your subscription ends, your world will be deleted, and you won't be able to put it on your singleplayer world list to play in single player, put it on a server, or if you buy realms again, upload it back up.