The Use of Google PAD Plugin

This document is kind of rude. Where should I store build.gradle in ? Which folder exactly ?
And [assetpackname] should be like pakchunk1-Android_ASTC ? If my chunk file named pakchunk1-Android_ASTC ??? So then where should I store it ? under [assetpackname]/src/main/assets ?

I got error like this !

Making .aab with Gradle...
UATHelper: Packaging (Android (ASTC)): To honour the JVM settings for this build a new JVM will be forked. Please consider using the daemon: https://docs.gradle.org/6.1.1/userguide/gradle_daemon.html.
UATHelper: Packaging (Android (ASTC)): Daemon will be stopped at the end of the build stopping after processing
UATHelper: Packaging (Android (ASTC)): Creating install-time assetpack for GooglePAD: assetpacks/install-time/obbassets
UATHelper: Packaging (Android (ASTC)): :assetpacks:install-time:obbassets
UATHelper: Packaging (Android (ASTC)): :assetpacks:fast-follow:pakchunk1-Android_ASTC
UATHelper: Packaging (Android (ASTC)): FAILURE: Build failed with an exception.
UATHelper: Packaging (Android (ASTC)): * Where:
UATHelper: Packaging (Android (ASTC)): Build file 'Z:\build.gradle' line: 1
UATHelper: Packaging (Android (ASTC)): * What went wrong:
UATHelper: Packaging (Android (ASTC)): A problem occurred evaluating root project 'app'.
UATHelper: Packaging (Android (ASTC)): > Plugin with id 'com.android.asset-pack' not found.
UATHelper: Packaging (Android (ASTC)): * Try:
UATHelper: Packaging (Android (ASTC)): Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
UATHelper: Packaging (Android (ASTC)): * Get more help at https://help.gradle.org
UATHelper: Packaging (Android (ASTC)): BUILD FAILED in 6s