Gradle error 'Unable to resolve dependency' could not find 'com.applovin:applovin-sdk'

I try to add AppLovin dependency but I get error like this:

ERROR: Unable to resolve dependency for ':app@debug/compileClasspath': Could not find 'com.applovin:applovin-sdk:+'. Show Details Affected Modules: app

ERROR: Unable to resolve dependency for ':app@debugAndroidTest/compileClasspath': Could not find 'com.applovin:applovin-sdk:+'. Show Details Affected Modules: app

ERROR: Unable to resolve dependency for ':app@debugUnitTest/compileClasspath': Could not find 'com.applovin:applovin-sdk:+'. Show Details Affected Modules: app

buildscript {
    repositories {
        maven { url 'https://plugins.gradle.org/m2/'}
    }
    dependencies {
        classpath 'gradle.plugin.com.onesignal:onesignal-gradle-plugin:[0.11.0, 0.99.99]'
    }
}
apply plugin: 'com.onesignal.androidsdk.onesignal-gradle-plugin'

repositories {
    maven { url 'https://maven.google.com' }
}
apply plugin: 'com.android.application'

repositories {
    jcenter()
}

repositories {
    // You can also use jcenter if you prefer
    mavenCentral()
}

android {

    compileSdkVersion 28
    buildToolsVersion '28.0.3'

    defaultConfig {
        applicationId 'com.example.application'
        minSdkVersion 21
        targetSdkVersion 28
        versionCode 2
        versionName '1.3'

        manifestPlaceholders = [
                onesignal_app_id: '1234567891011121314',
                // Project number pulled from dashboard, local value is ignored.
                onesignal_google_project_number: 'REMOTE']
    }

    lintOptions {
        disable 'MissingTranslation'
    }

    buildTypes {
        release {
            minifyEnabled false
            shrinkResources false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:animated-vector-drawable:28.0.0'
    implementation 'com.android.support:support-v4:28.0.0'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
    implementation 'com.android.support:cardview-v7:28.0.0'

    implementation 'com.onesignal:OneSignal:[3.9.1, 3.99.99]'

    implementation 'com.daimajia.numberprogressbar:library:1.4@aar'
    implementation 'com.amitshekhar.android:android-networking:0.2.0'
    implementation 'com.google.code.gson:gson:2.7'
   // implementation 'com.google.android.gms:play-services-ads:17.1.2'

    implementation 'com.airbnb.android:lottie:2.7.0'
    implementation 'com.jwang123.flagkit:flagkit:1.0'
    implementation 'fr.bmartel:jspeedtest:1.32.1'
    implementation 'com.github.anastr:speedviewlib:1.1.0'
    implementation 'agency.tango.android:material-intro-screen:0.0.5'
    implementation 'com.yarolegovich:lovely-dialog:1.1.0'
    implementation 'com.getkeepsafe.taptargetview:taptargetview:1.12.0'
    implementation 'com.google.firebase:firebase-core:16.0.6'
    implementation 'com.google.firebase:firebase-messaging:17.3.4'

    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'

    // Required Dependency by Audience Network SDK
    implementation 'com.android.support:support-annotations:28.0.0'
    implementation 'com.facebook.android:audience-network-sdk:5.4.1'

    implementation "'com.applovin:applovin-sdk:+'"
}
apply plugin: 'com.google.gms.google-services'

In your build.gradle file, remove the quotation marks (" ") from the line with the applovin-sdk implementation dependency.

From:

dependencies {

    implementation "'com.applovin:applovin-sdk:+'"
}

To:

dependencies {

    implementation 'com.applovin:applovin-sdk:+'
}