Azure SQL Database

We are embarking on a project of building a Django web application on Microsoft Azure. The debate holding us back is whether to with Azure SQL Database or Azure Database for PostgreSQL. From all the tutorials and video tutorials they use Azure Database for PostgreSQL but one team member is insisting on Azure SQL Database. Please advise of what to consider if I capitulate what database do I need to install locally to get the project moving.

Hi, I am trying to build a billing system for utilities. It will have a web app and a mobile app too. The USP of this system would be that the mobile application would support offline syncing, basically, let's say while doing the payment the internet goes down then when it's back the payment goes through. Basically, some features could work offline. So I am confused as to which DB to go for. A relational one like Azure SQL Database or a non-relational one like MongoDB?