For an Android 6.0.1 (Marshmallow) device, Nova Launcher 6.0
Android 6.0.1 Marshmallow is now considered a legacy operating system. To run Nova Launcher Prime effectively, you should target Version 6.x or early 7.x nova launcher prime apk android 601
The free version is too new for the old unlocker. Fix: Ensure both Free and Prime are from the same major version (e.g., 6.x Free + 6.x Prime). For an Android 6