Android Studio – How to make broadcastreceiver work on MIUI when phone is asleep?

class AlarmReceiver : BroadcastReceiver() {

    override fun onReceive(context: Context, intent: Intent) {
        Toast.makeText(context,"Ready to wake up?", Toast.LENGTH_LONG).show()

        val myIntent = Intent(context,AlarmActivity::class.java)
        myIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
        context.startActivity(myIntent)
    }
}

Manifest:

<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/Theme.QuickNap">
        <activity android:name=".AlarmActivity"
            android:screenOrientation="portrait"
            android:theme="@style/Theme.NoActioBar"
            android:windowSoftInputMode="adjustResize"></activity>

<!--        <receiver-->
<!--            android:name=".AlarmReceiver"-->
<!--            android:process=":remote" />-->

        <receiver android:name=".AlarmReceiver"
            android:enabled="true"
            android:exported="true"
            android:process=":remote">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
                <action android:name="android.intent.action.QUICKBOOT_POWERON" />
                <action android:name="android.intent.action.REBOOT"/>
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </receiver>

        <activity
            android:name=".MainActivity"
            android:screenOrientation="portrait"
            android:theme="@style/Theme.NoActioBar"
            android:windowSoftInputMode="adjustResize">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

MainActivity:

  onTimer = true;
        moonImage.setColorFilter(null)
        val mIntent = Intent(this, AlarmReceiver::class.java)
        val mPendingIntent = PendingIntent.getBroadcast(this, 0, mIntent, PendingIntent.FLAG_UPDATE_CURRENT)
        val calendar = Calendar.getInstance()
        calendar.add(Calendar.SECOND, minuteSet)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
        {
            alarmManager.setAndAllowWhileIdle(AlarmManager.RTC_WAKEUP,calendar.timeInMillis,mPendingIntent)
        }
        else
        {
            alarmManager.set(AlarmManager.RTC_WAKEUP, calendar.timeInMillis, mPendingIntent)
        }

hi, i am trying to create a alarm android app using kotlin .
so i created a Reciever, in that reciever i am switching on a activity and in that activity i am playing Sound.

this code works fine as intended on emulator. but on device (Redmi Note 7 pro, MIUI OS). it only works when screen is on and if the app is open.
any idea on how to make sure it switches the screen on when this receiver is invoked?

also i am new to android development, so ELI5. ty