Hello Brian Lee,
the reason you don't see the module in the navigation and why you get the security exception when you try to navigate to it is one and the same, you do not have permissions to access that module.
Please log in with the admin account, go to that module and make sure you have permissions to at least View the module.
I hope you'll find this information helpful. Let us know if there is anything else we can do for you.
the Telerik team