You can do that with zapier it will allow you to have 5 zaps for free but also the free version pull the changes every 15 minutes
You need to add the case to verify your webhook: case 'hook.verify': PodioHook::validate($_POST['hook_id'], array('code' => $_POST['code'])); break; Try this, i'm sure it will work!...
You are using the app_item_id and not the item_id. Go to your item, click the "Actions" dropdown at the top and pick the "Developer" option. There you can see the item_id -- it will be a much larger number
When you authenticate as an app you only have access to items in that specific app. You don't have access to all workspace contacts, only those created by the app or already in use in that app.