You are looking for "high-quality" in terms of stability—versions that work without crashing constantly.

: Another highly reputable alternative that archives older versions of apps, making it easy to find a build that still runs on KitKat.

For a KitKat user, F-Droid is invaluable. Because the apps are often developed by individuals or small teams with a focus on efficiency and privacy, they are frequently lightweight, ad-free, and have minimal system requirements. They are also less likely to have "phoned home" dependencies to Google Play Services, meaning they often remain fully functional long after official support for an OS version has ended. Many essential open-source apps continue to release builds for Android 4.4.

Open your local File Manager app and locate your downloaded files.