Hi djackson26, it seems that the server has ran out of space on disk C due to activity not related to unreal, and that has caused the server to crash. Thanks for letting me know, I’ve cleaned up the space and restarted the server, you should be able to log in fine now. 
Hi Agentleo, and thanks for purchasing. I’m currently thinking of removing the desert demo altogether from the distributed kit since it can be taken from the official vehicle game project anyways.
This has been advised previously by qdelpeche and it will be added in the next update, along with some security fixes.