Is the email address entered correctly in Once Setup?
In Once Setup, press the Application Settings button 
and go to the Account tab.
Here, check that the Email for receiving orders is the correct email address.
Are the emails being sent to your Spam folder?
Some email system's spam filters can put Once Worksheet emails into the Junk or Spam email folders. If this is happening, you'll need to follow your email system's instructions for how to make sure emails from Once Mobile are not marked as spam.
For example, the Microsoft Office 365 default spam filter is putting our Worksheets into the Junk Email folder.
To fix this, open an email in the Junk Email folder and click on the “it’s not spam” link.
Have you pressed the 'Send Orders' button in Once Mobile?
After completing an order/quote and choosing the Mark as Complete and ready for sending option on the Complete screen, you will need to press the Send Orders button on the home screen to send the orders/quotes to customers and worksheets to your business. This extra step is to enable Once Mobile to be used without an internet connection. For example, you can be out surveying orders all day without needing an internet connection. When you return to your shop/home and have WiFi, you can then press Send Orders and send all of the day's orders.