```dart
import 'package:amplify_flutter/amplify_flutter.dart';
import 'package:amplify_storage_s3/amplify_storage_s3.dart';

Future<void> downloadProtectedFile({
  required String key,
  required String targetIdentityId,
  required String downloadPath,
}) async {
  final awsFile = AWSFile.fromPath(downloadPath);
  final options = StorageDownloadFileOptions(
    // specify that the file has a protected access level
    accessLevel: StorageAccessLevel.protected,
    // specify the identity ID of the user who uploaded this file
    pluginOptions: S3DownloadFilePluginOptions.forIdentity(
      targetIdentityId,
    ),
  );

  try {
    final result = await Amplify.Storage.downloadFile(
      key: key,
      localFile: awsFile,
      options: options,
    ).result;

    safePrint('Downloaded file is located at: ${result.localFile.path}');
  } on StorageException catch (e) {
    safePrint('Something went wrong downloading the file: ${e.message}');
    rethrow;
  }
}
```