Hi,
Please confirm when you completed the Exercise back in Unit 3, Task 1, step 2, that everything completed without any error messages? This is essential for you to get the expected results in the Configure network access (Unit 9) exercise you are on now.
Based on what you wrote you confirmed that the NSG is allowing port 80, but you get no response from your curl command, which means Nginx is not listening/responding.
What I recommend is to jump back to the Unit 3 - Exercise - Create an Azure Virtual Machine exercise using the "Unit x of 14" dropdown menu at the top, Activate a new Sandbox, re-do the exercise, then jump back to Unit 9 exercise and complete that again. The sandbox is only valid for 1 hour max, which is why I'm asking you to activate a fresh one so you will have time to complete both exercises.
If you come back here and post any error messages you may receive I can help.
Thanks.
-TP