I am not getting email notifications from the Contact Us form submissions

This artcile specifically addresses the built in Contact Us form that comes with the website and not any profile form that you create.

You should be getting an email notification for every contact us form submission on your website. 
The email address to which these notifications are sent to is the primary email address on your Organizations contact profile in the CRM. 
Verify that your organization's profile in the CRM has your correct email address. 

An easy way to find the correct contact profile is to go to the quick search in the CRM and type in the number 1 and select contact id from the options.