laravel download file from rest api with guzzle

I am trying to fetch a file from REST API endpoint via POST request, and then return it to browser.

1. User fills in the form, and requests for file download.
2. controller forms a request body from form parameters, and calls REST API endpoint.
3. API either sends a file directly or a json on case of failed resultset.

I am trying to get this file in the controller and then redirect it to client.

I am using Guzzle for this.

public function downloadMatchedSkusWithTags() {
    $inputParams = [];
    $inputParams['client_name'] = $this->request->input('dw_client_name');
    $inputParams['from_date'] = $this->request->input('dw_from_date');
    $inputParams['to_date'] = $this->request->input('dw_to_date');
    $inputParams['tags'] = $this->request->input('dw_tags');
    if(!empty($inputParams['tags']))
        $inputParams['tags'] = implode("|", $inputParams['tags']);

    $inputParams = array_map(array($this, 'sanitizeInputParams'), $inputParams);
    $filterArr = array_filter($inputParams);
    $client = new Client(["base_uri" => $this->apiBaseUrl]);
    $url = 'download/filterdownload/';
    try {
        $response = $client->post($url, ['headers'=>['Content-Type' => 'application/json'], 'body'=>json_encode($filterArr)]);
        $file = $response->getBody()->getContents();
        return $file;
    } catch (\Exception $e) {
        return redirect()->back()->with('error', $e->getMessage());
    }

    if(!empty($resArr) && array_key_exists('response', $resArr))
        return redirect()->back()->with('error', $resArr['response']);
}

Here's my controller method.

But this only redirects me to a blank page and no download.

via Chebli Mohamed