you dont need android studio search on the playstore for an apk signer or if you dont find anything search for an apk renamer pretty sure it would resign the app
well I did what you said and installed the apk signer and used it and it actually installed. But now when i try to play it goes to a black screen and closes out of the game
worst case the game isn't build for your phone you'd need a pc and the original project to fix it but maybe it just the app you used that broke something