I'm having no luck at getting Outlook Add-Ins deployed to my GCC users. Whenever I go to click on Get Add-Ins in Outlook desktop it dumps me to OWA with no option to adding any items from the online store.
Are Add-Ins even supported in GCC tenants?
C_the_S Hello Cary, I am not that familiar with the GCC plans but fortunately MS docs are great. Scroll down a bit here https://docs.microsoft.com/en-us/office365/servicedescriptions/office-365-platform-service-description/office-365-us-government/office-365-us-government#office-application-availability-and-enterprise-value
You'll see that it's supported in the G3 and G5 plans.
C_the_S I recently had the same experience as you, and after submitting a support ticket that made it's way up to the Product Group I finally have an answer.
GCC supports Add-ins, but they can only be deployed by the admin through a forced deployment in the admin center. Users are not able to obtain add-ins via the Get Add-ins button in Outlook desktop or OWA. Even circumventing this and going to AppSource directly to obtain the add-in will not work because the tenant will block them from attaching to the mailbox.
I know this answer is a year later, but I hope this helps!
I had success using the Help & Support in admin center. I entered "deploying add-ins missing" and the article listed notes to try. The last one provided a link that worked. Here is the link: https://admin.microsoft.com/Concierge/RedirectToArticle?uri=https%3A%2F%2Fadmin.microsoft.com%2FAdminPortal%2FHome%3F%23%2FSettings%2FAddIns&solutionType=AlchemyInsight&title=Deploying%20add-ins%20for%20Microsoft%20365%20Apps&clientAppName=SupportCentralSearch
Hope that helped
