Go to Settings > Security and toggle on "Install apps from Unknown Sources."
For the most secure experience, you can find the official version through the App Cloner Home Page or the Google Play Store . App Cloner - Official Home Page App Cloner Mod Apk V2.19.0 -Premium Unlocked-
Some users want to clone their default Dialer or Settings app. V2.19.0 allows this, but you must enable "Root mode" inside App Cloner settings. Without root, system apps are read-only. Go to Settings > Security and toggle on