Register library activity in manifest

<?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"



package="com.fitnesscircle.snapo">


<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />


<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">


    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>


<activity
    android:name="com.afollestad.materialcamera.CaptureActivity"
    android:label="@string/app_name"
    android:theme="@style/MaterialCamera.CaptureActivity" />
<activity
    android:name="com.afollestad.materialcamera.CaptureActivity2"
    android:theme="@style/MaterialCamera.CaptureActivity" />
<activity
    android:name="com.afollestad.materialcamera.MaterialCamera"
     />

Even though i register its still says cant find explicit activity class. am new to android coding. is anything i need to change so i get rid of this ActivityNotFoundException

Unable to find explicit activity class {com.fitnesscircle.snapo/com.afollestad.materialcamera.CaptureActivity}; have you declared this activity in your AndroidManifest.xml

please help