Hello soso2565,
yes it's a littele bit late for an answere.
I'll try it in english ( native german speaker)....
Please download "OsmAnd ". Create an local directory like "MAPS" on your android device and put .maps inside.
Open OsmAnd and navigate to folder, open .map.
If you don'T want to install software, use Google Files, locate your test.map file
and select "Open With" > OsmAnd.
Hope this will work for you,
greetings from Northern Germany (Baltic Sea)