Open your "Downloads" folder, tap the file, and follow the prompts. Google Help Important Warnings Security Risks:

Open your current browser (even the old stock Android browser will work). Navigate to a trusted mirror.

The APK is corrupt or for a different CPU architecture (e.g., x86). Download the armeabi-v7a version again from a clean source. Also, ensure the file name ends with .apk and not .bin .