Hi,
Please make sure you Activate a new sandbox and complete Unit 3 Exercise - Create an Azure Virtual Machine right before you attempt to complete Unit 9 Exercise - Configure Network Access. These two exercises are intended to be completed in one sitting, within the 1 hour sandbox lifetime.
If the above is helpful please click Accept Answer. If you follow the above and you still have issues please copy the error message(s) you are receiving and the precise step you are attempting when the error occurred and post in a comment below. Thanks.
-TP