Hi Dmitrij!
You are requiered to upload the executable (and all the files it needs to run the game - in your case, the .apk is all you need). But you can upload other files as well if you'd like.
If you link it trough Google Drive, people without a google drive account won't be able to aces the files. You could upload the file directly on itch.io when you post your game, or if you would rather keep them on a hosting service, I'd recommend dropbox.
Hope this has been of some help for you.
-Andrei