Here is how to download a Map into Minecraft PE for Android.
First, go to a website that you trust that contains MCPE Maps. Then download the map you wish to download. Then launch Google Play and get AndroZip.
Then launch AndroZip. You should get welcomed.
Navigate to the Downloads folder and find the maps archive file. Tap on the archive and press extract to.
Navigate to /storage/emulated/0/games/com.mojang/minecraftWorlds. Then click extract here.
You have now got your map into Minecraft PE. Launch and play!
Depending on how old the map is, it may appear far down your worlds list.
Epic Chas Gamer 😀
PS: You see that like button? Smash it to pieces!