When you use the newer .apk, it should give you the option to update the existing game files. Your save files are still available after the update.The "update files only" .zip is not for android.
I am using apk version 22.09.13 And it doesn't give me the option to update the game. I'm really worried if my 80hours are lost :(
Are you using the itch app instead of directly downloading the file?The newest apk is 22.09.29.