So you are running into two different issues here. The first one is that Unity does not work with JDK9 for now, so please use JDK8 instead (you can find more info here Java 9 (JDK 9) support by Unity Android ). The other issue is exactly what I’ve said before
This means that selecting Target SDK Level from 21 to 23 will fail. So you should select 24 or higher. Please note, that “target sdk level” doesn’t mean the only version where your application works. It means that this is the latest version which you have tested, but your application will run on older Android versions as well (see more info here <uses-sdk> | Android Developers ). So setting the latest available (or auto) is fine.