Can't import Google Asset Delivery (Install-Time)

Question

so I'm following the guide, but it gets error once I imported the asset-pack plugin in the library's gradle.

plugins {
    id 'com.android.library'
    id 'org.jetbrains.kotlin.android'
    id("com.android.asset-pack")
}

Error:

An exception occurred applying plugin request [id: 'com.android.asset-pack']

Failed to apply plugin 'com.android.asset-pack'. Cannot add extension with name 'kotlinOptions', as there is an extension already registered with that name.

but if I deleted all the library's gradle and just put the asset-pack plugin and tag, it works but I get the errorCode -2. What did I miss on the asset-pack delivery setup?

plugins {
    id("com.android.asset-pack")
}

assetPack {
    packName = "packName" 
    dynamicDelivery {
        deliveryType = "install-time"
    }
}

ps. my gradle is already at 7.1.3