Gauri Mahajan explains how continuous backup works in Cosmos DB:
To follow the exercise in this article, we would need an Azure Account with administrative privileges to operate the Azure Cosmos DB service. It is assumed that such an Azure Account and setup is already available and ready for use. The Continuous backup option is not available for all the editions of Cosmos DB and works only under certain configurations. The focus of this exercise is to understand the use-cases and options under which continuous backup would work in Cosmos DB.
There are four restrictions (as of the draft of this article), which should be kept in view while considering using continuous backup.
Read on for those restrictions and then how you can configure continuous backup to run.