flutter audio_service not working, errors in AndroidManifest.xml - flutter

Question

I am attempting to recreate the audio_service tutorial on GitHub and it is not working, no sound is playing when you click the play button. I have observed an error in the AndroidManifest.xml which seems to be related - the documentation of course requires you add lines to the AndriodManifest.xml file.
However I am getting errors on the lines and which I suspect could be causing the problem. The errors are "Class referenced in the manifest, _______ , was not found in the project or the libraries / Unresolved package '___' " for both.
I did include these dependencies in my pubspec.yaml:
audio_service: ^0.15.1
just_audio: ^0.5.2
Note that I am having the same problem on both my Windows 10 development environment and on my MacBookPro running Catalina. Does anyone know how I can resolve this? What am I missing?
Here is my complete AndroidManifest.xml file:
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="tv.realhelp.new_audio_service_test">
<uses-permission android:name="android.permission.WAKE_LOCK"/>
<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
<!-- io.flutter.app.FlutterApplication is an android.app.Application that
calls FlutterMain.startInitialization(this); in its onCreate method.
In most cases you can leave this as-is, but you if you want to provide
additional functionality it is fine to subclass or reimplement
FlutterApplication and put your custom class here. -->
<application
android:name="io.flutter.app.FlutterApplication"
android:label="new_audio_service_test"
android:icon="#mipmap/ic_launcher"
android:usesCleartextTraffic="true">
<activity
android:name=".MainActivity"
android:launchMode="singleTop"
android:theme="#style/LaunchTheme"
android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
android:hardwareAccelerated="true"
android:windowSoftInputMode="adjustResize">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<!-- Don't delete the meta-data below.
This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
<meta-data
android:name="flutterEmbedding"
android:value="2" />
<service android:name="com.ryanheise.audioservice.AudioService">
<intent-filter>
<action android:name="android.media.browse.MediaBrowserService" />
</intent-filter>
</service>
<receiver android:name="com.ryanheise.audioservice.MediaButtonReceiver" >
<intent-filter>
<action android:name="android.intent.action.MEDIA_BUTTON" />
</intent-filter>
</receiver>
</application>
</manifest>