How to use Cotter as an alternative for Firebase to verify phone?

Question

I want to use Cotter as an alternative for Firebase to verify phone. I followed the steps on: Cotter page: Verifying email and phone number in your mobile app using our Android SDK

But I get this error when trying to sync the gradle: Failed to resolve: com.github.cotterapp:android-sdk:0.3.0

Code is:

dependencies {
implementation fileTree(dir: 'libs', include: ['*.jar'])

implementation 'androidx.appcompat:appcompat:1.2.0'
implementation 'androidx.preference:preference:1.1.1'
testImplementation 'junit:junit:4.13'
androidTestImplementation 'androidx.test.ext:junit:1.1.2'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'

implementation 'com.google.android.material:material:1.2.0'
implementation 'androidx.constraintlayout:constraintlayout:2.0.1'
implementation 'androidx.navigation:navigation-fragment:2.3.0'
implementation 'androidx.navigation:navigation-ui:2.3.0'
implementation 'androidx.legacy:legacy-support-v4:1.0.0'
androidTestImplementation 'androidx.test.ext:junit:1.1.2'
implementation 'com.android.volley:volley:1.1.1'
implementation 'com.github.barteksc:android-pdf-viewer:2.8.2'

//Cotter
implementation 'com.github.cotterapp:android-sdk:0.3.0'
}

And I also want to know how to do this: For step 2 I need to Initialize Cotter with your API_KEY_ID. Using this code:

Cotter.init(this.getApplicationContext(), 
         "https://www.cotter.app/api/v0",
         <API_KEY_ID>);

Where must I put this code?