Enable installs from unknown sources
Android 8.0+: Settings → Apps or Apps & notifications → Special app access → Install unknown apps → choose Chrome or Files → Allow from this source.
Android 7.1 and below: Settings → Security → Unknown sources → On.
Install the APK
Download the APK. Open Files or My Files → Downloads → tap the APK → Install → Open.
If it’s blocked, enable “Allow from this source” for the app you’re using, then try again.