After I deployed the Azure B1 VM (HKD 1000/month for each instance) and git committed my code to the Azure App service, the web page showed the default Azure page.

However, when I changed the pricing plan to a more expensive Production Premium server (>HKD 400/month for each instance) and deployed 2 such VMs to prevent single-point failure. Now, the page does not show the default Azure page and everything is good.