Some customers have their Office 365 environments configured under government cloud options. This is for privacy-sensitive customers in local, state, and national government organizations. Due to the more restricted nature of these environments, which is important for the customers’ privacy and security needs, not all resources typically available in a standard production environment are available within these clouds.
More on that here.
Although it is possible to deploy add-ins in these environments, the current architecture of ExtendSync and ExtendInsights is not ready to support this. It would require significant development efforts with lots of unknown variables.
Ultimately, we respond that the current version of the add-in is not yet capable of running on government cloud environments. This would require enormous changes to the product's architecture, which we will have to consider in the future.