https://www.juniper.net/documentation/us/en/software/session-smart-router/docs/plugin_cloud_ha/
In cloud environments such as AWS, Azure, etc., any techniques that rely on broadcast and multicast are not supported.
Azure HA is possible there are just many flavors and the recommended would be dual router in Azure with iBGP between SSR routers and BGP over SVR to other SSR sites w/ BGP to Azure via the ARS - some testing with ARS is still needed.