The term "portable" in this context likely refers to the ability to carry and use the KingRoot application on multiple devices without the need for installation on a host computer. The KingRoot APK itself is a self-contained file that can be easily transferred and used across different Android devices.

Since you are installing an APK outside the Google Play Store:

Do not download from random pop-up ads. Use a trusted mirror. For Android 4.4.2, the best versions are KingRoot v4.9.6 or v5.4.0 (newer versions may lag on old hardware).

Android 4.4.2 marked a transition point in Android security. It introduced improvements in SELinux (Security-Enhanced Linux) enforcement, though it was not as stringent as later versions (e.g., Android 5.0 Lollipop). The kernel version usually associated with KitKat (predominantly Linux kernel 3.4.x) contains known vulnerabilities that are now well-documented, making it a prime target for automated rooting tools.