Since you are not using the Play Store, you need to allow your browser or file manager to install APKs. Go to your Android Settings -> Security -> Enable Install from unknown sources for your browser app.
As Minecraft has evolved significantly since Alpha 1.0.16_02, you may want to consider downloading the latest version of Minecraft from the Google Play Store or the official Minecraft website. The latest versions offer improved performance, new features, and better compatibility with modern devices. Minecraft Alpha 1.0 16 02 Download Apk Android -UPDATED
For an updated Alpha build, you are looking for community projects like: Since you are not using the Play Store,
Alpha 1.0.16_02 was coded strictly in Java for desktop computers. Minecraft Alpha 1.0 16 02 Download Apk Android -UPDATED