DownloadFileWithFileIdentifier Samplecode is Running.. 
CyberSource\ApiException Object
(
    [responseBody:protected] => stdClass Object
        (
            [response] => stdClass Object
                (
                    [rmsg] => Authentication Failed
                )

        )

    [responseHeaders:protected] => Array
        (
            [0] => HTTP/1.1 401 Unauthorized
            [Strict-Transport-Security] => max-age=31536000
            [v-c-correlation-id] => 4078e817-667e-4ec5-83a9-dc4c4be075ef
            [content-type] => application/json
            [v-c-response-time] => 1765829173
            [content-length] => 45
            [X-OPNET-Transaction-Trace] => 92e978e2-5f8b-4832-be37-e9b99497de00-1816387-22051896
        )

    [responseObject:protected] => 
    [message:protected] => [401] Error connecting to the API (https://api.cybersource.com/sfs/v1/files/QmF0Y2hGaWxlc0RldGFpbFJlcG9ydC5jc3YtMjAxOS0wOS0zMA%3D%3D?organizationId=testrest)
    [string:Exception:private] => 
    [code:protected] => 401
    [file:protected] => /opt/bitnami/apache/htdocs/cs4/vendor/cybersource/rest-client-php/lib/ApiClient.php
    [line:protected] => 309
    [trace:Exception:private] => Array
        (
            [0] => Array
                (
                    [file] => /opt/bitnami/apache/htdocs/cs4/vendor/cybersource/rest-client-php/lib/Api/SecureFileShareApi.php
                    [line] => 172
                    [function] => callApi
                    [class] => CyberSource\ApiClient
                    [type] => ->
                )

            [1] => Array
                (
                    [file] => /opt/bitnami/apache/htdocs/cs4/vendor/cybersource/rest-client-php/lib/Api/SecureFileShareApi.php
                    [line] => 102
                    [function] => getFileWithHttpInfo
                    [class] => CyberSource\Api\SecureFileShareApi
                    [type] => ->
                )

            [2] => Array
                (
                    [file] => /opt/bitnami/apache/htdocs/cs4/Samples/SecureFileShare/CoreServices/DownloadFileWithFileIdentifier.php
                    [line] => 16
                    [function] => getFile
                    [class] => CyberSource\Api\SecureFileShareApi
                    [type] => ->
                )

            [3] => Array
                (
                    [file] => /opt/bitnami/apache/htdocs/cs4/Samples/SecureFileShare/CoreServices/DownloadFileWithFileIdentifier.php
                    [line] => 32
                    [function] => DownloadFileWithFileIdentifier
                )

        )

    [previous:Exception:private] => 
)
[401] Error connecting to the API (https://api.cybersource.com/sfs/v1/files/QmF0Y2hGaWxlc0RldGFpbFJlcG9ydC5jc3YtMjAxOS0wOS0zMA%3D%3D?organizationId=testrest)