Failed to resolve: com.android.support:support-v4:30.0.0

It Shows:
Failed to resolve: com.android.support:support-v4:30.0.0
Add Google Maven repository and sync project
Show in Project Structure dialog
Affected Modules: app

build.gradle(:app):

apply plugin: 'com.android.application'

android {
compileSdkVersion 30
buildToolsVersion '30.0.2'

defaultConfig {
    applicationId "com.example.android.miwok"
    minSdkVersion 15
    targetSdkVersion 30
    versionCode 1
    versionName "1.0"
}
buildTypes {
    release {
        minifyEnabled false
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
}

}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    testImplementation 'junit:junit:4.12'
    implementation 'com.android.support:appcompat-v7:30.0.0'
    implementation 'com.android.support:support-v4:30.0.0'
    implementation 'com.android.support:design:30.0.0'
}

Use the androidx library mostly you need to use this now:

To use this you need to add Androidx support to your project if it is not migrated to Androidx.

You can find here how to migrate project to Androidx.

implementation 'androidx.appcompat:appcompat:1.2.0'

or use the last support library:

implementation 'com.android.support:appcompat-v7:28.0.0'

It is because the support libraries you trying to use don't exist.

For Add Google Maven repository and google() do this inside build.gradle which outside of app directory.

allprojects {
    repositories {

        google()
        maven {
            url 'https://maven.google.com'
        }
     
        jcenter()
    }
}

The support libraries v30 don't exist.
Remove them.

Use the androidx libraries:

    implementation 'androidx.appcompat:appcompat:1.2.0'
    implementation 'androidx.legacy:legacy-support-v4:1.0.0'
    implementation 'com.google.android.material:material:1.2.1'

To use them you have to add the google() repo in your top-level build.gradle file:

allprojects {
    repositories {
        google()
        jcenter()
    }
}