I bought multiple games none of which work because when I try and download them on my Android phone I get a single green app that's less than the total download that when I try and install says problem parsing package ( each of these games is over 1 gig in size and the file that shows up is something like 345mgb). I've also ended up with a zip file on some games that has to my knowledge no working game app it just has the files that can't be viewed. Any help is appreciated.

For Android you need to download a file ending in .apk.  If there isn't one, then it won't work on your Android device and it should be played on a pc or other device.

That error (unable to parse) often indicates the games require an Android version, or features that your phone doesn't have. For example, if the developer set the game's minimum requirements to Android 9 or over and you have Android 7, you'll get that message. It can also happen with the graphics.  It would be best to ask on the actual game page if  possible, because the developer can tell you what settings they require.  These settings will be different for every game on itch.io.