...
        // Create a client.
        $chatServiceClient = new ChatServiceClient([
                'credentials' => "$keyPath/songanhbot-sa-02.json",
            ]
        );

        // Prepare the request message.
        $request = (new CreateMessageRequest())
            ->setParent($space)
            ->setMessage((new Message())->setText($messageText));

        // Call the API and handle any network failures.
        try {
            $chatServiceClient->createMessage($request);

            $request = (new UploadAttachmentRequest())
                ->setParent($space)
                ->setFilename($filePath);

            try {
                $response = $chatServiceClient->uploadAttachment($request);
            } catch (ApiException $ex) {
                printf('Call failed with message: %s' . PHP_EOL, $ex->getMessage());
            }
        } catch (ApiException $ex) {
            printf('Call failed with message: %s' . PHP_EOL, $ex->getMessage());
        }

I have coded this to send message and upload attachment to a Space within a Workspace.

The code can send the message successfully but failed for uploading the attachment, here is the error print from the code:

Call failed with message: {
    "message": "This method doesn't support service account authentication. Authenticate with a user account.",
    "code": 7,
    "status": "PERMISSION_DENIED",
    "details": [
        {
            "@type": "type.googleapis.com\/google.rpc.Help",
            "links": [
                {
                    "description": "See article Authenticate as a user.",
                    "url": "https:\/\/developers.google.com\/chat\/api\/guides\/auth\/users"
                }
            ]
        }
    ]
}

The json key file is for a service account which has already been added to Domain wide delegation via Workspace Admin(Api Controls).

The scopes enables:

I use PHP yii2 framework version: 2.0.51 and google/apps-chat version: 0.10

Please help!