Can't find examples for TranscriptOutputConfig or how retrieve async operations

[TalesFromTheNetworkRoom]

Good morning,
I'm currently writing a small php program with a web interface to allow my client to transcribe lenghty audio records.

1.I succesfully applied the function transcribe_async_gcs and tested it.
I was looking at this page "Method: speech.longrunningrecognize" the section which describe:

"outputConfig": {
object ([TranscriptOutputConfig])
}

object ([TranscriptOutputConfig])

Optional. Specifies an optional destination for the recognition results.

But for the love of my sanity I couldn't find any apllicable example for php.
Looking inside the speech to text package I found some uses for this object so I tried to write something like this:

use Google\Cloud\Speech\V1\TranscriptOutputConfig;

    // set output bucket
    $output = (new TranscriptOutputConfig())
        ->setGcsUri('gs://my_bucket/'.$fileName.'.txt');

and then: $operation = $client->longRunningRecognize($config, $audio, [$output]); -> output as array
But to no success, it didn't produce any text file in my bucket.
What am I missing? If there are any examples or documentation that I did not find could you please point me to it? Thanks.

2. The second problem is related to the time to process the file, looking at the function transcribe_async_gcs:

// create the asyncronous recognize operation
$operation = $client->longRunningRecognize($config, $audio);
$operation->pollUntilComplete();

if ($operation->operationSucceeded()) {
    $response = $operation->getResult();

    // each result is for a consecutive portion of the audio. iterate
    // through them to get the transcripts for the entire audio file.
    foreach ($response->getResults() as $result) {
        $alternatives = $result->getAlternatives();
        $mostLikely = $alternatives[0];
        $transcript = $mostLikely->getTranscript();
        $confidence = $mostLikely->getConfidence();
        printf('Transcript: %s' . PHP_EOL, $transcript);
        printf('Confidence: %s' . PHP_EOL, $confidence);
    }
} else {
    print_r($operation->getError());
}

$client->close();

$operation->pollUntilComplete(); --> this part does not run async, it makes my controller wait for the function be finished.
I found this old thread on stack that goes like this:
(https://stackoverflow.com/questions/55316150/how-to-resume-google-cloud-speech-api-longrunningrecognize-timeout-on-cloud-fu)

$operationName = $operation->getName(); -> gets operation name, I manage to get this to work with mine as well.

then in a separate controller:

CloudSpeech::initOnce();
$newOperationResponse = $speechClient->resumeOperation($name, 'LongRunningRecognize');

if ($newOperationResponse->operationSucceeded()) {
$result = $newOperationResponse->getResult();

}

But it doesn't work with mine, I get thi error:

Error occurred during parsing: Class google.cloud.speech.v1.LongRunningRecognizeMetadata hasn't been added to descriptor pool.

I think I need to add somenthing but then again, there are no examples so I'm stuck at this point.
Sorry I posted such a lengthy question, but I'm getting desperated a this point.
Thanks in advance.