OfflineMaps

Download maps from geofabrik:

http://download.geofabrik.de

Maps have the extension [.osm.bz2]

Extract your map into the folder:

sdcard/Android/data/com.khawarezm.offlinemaps/map.osm

In Android settings, grant OfflineMaps the permissions to access location and storage

Restart OfflineMaps so that it starts reading the [.osm] file; this may take some time depending on the size of the map.