i modified the config.xml like you said, adding the plugin and still not working
<?xml version='1.0' encoding='utf-8'?>
<widget android-versionCode="1000000" id="com.avisos.miavisos" version="1.0.0.0" xmlns="http://www.w3.org/ns/widgets" xmlns:cdv="http://cordova.apache.org/ns/1.0">
<feature name="ConstructAd">
<plugin name="cocoon-plugin-ads-android-admob" spec="~1.0.6" />
<param name="android-package" value="com.scirra.ConstructAd" />
</feature>
<feature name="Whitelist">
<param name="android-package" value="org.apache.cordova.whitelist.WhitelistPlugin" />
<param name="onload" value="true" />
</feature>
<name>adstertes</name>
<description>avisos</description>
<author />
<allow-intent href="http://*/*" />
<allow-intent href="https://*/*" />
<icon density="xxxhdpi" height="512" src="www/icons/icon-512.png" width="512" />
<icon height="256" src="www/icons/icon-256.png" width="256" />
<icon density="xhdpi" height="128" src="www/icons/icon-128.png" width="128" />
<icon density="mdpi" height="64" src="www/icons/icon-64.png" width="64" />
<icon height="32" src="www/icons/icon-32.png" width="32" />
<icon height="16" src="www/icons/icon-16.png" width="16" />
<access origin="*" />
<preference name="loglevel" value="DEBUG" />
<preference name="orientation" value="portrait" />
<preference name="fullscreen" value="false" />
<preference name="DisallowOverscroll" value="true" />
<preference name="android-minSdkVersion" value="21" />
<preference name="android-targetSdkVersion" value="23" />
</widget>