Required Message Queues warning is issued in the following situation:
Message Queues Component, required to send and receive SMS, are not correctly installed. Application runtime errors might occur.
You have a SMS flow or any SMS elements such as Start iSMS, Send Message or Send Bulk Messages, in your module and no Message Queues are available.
To use SMS flows or any kind of SMS interactions in web flows, you must install Message Queues Component in your server. If you don't install this component, your application might not work as expected. Contact your Service Center administrator and ask Message Queues Component to be installed and configured.