As an admin, you can deploy Office add-ins to the users in your organization by using the Centralized Deployment feature in the Microsoft 365 admin center. Centralized Deployment is the recommended and most feature-rich way for most admins to deploy add-ins to users and groups within an organization.
In the admin center, go to the Settings > Integrated apps > Add-ins page (If you don't see the Settings > Integrated apps page, go to the Settings > Add-ins page)
2. Click Deploy Add-in at the top of the page, and then click Next.
3. Click Upload custom apps
4. Download manifest.xml from https://gitlab.com/new_old_stamp/office-addins/-/blob/main/public/manifest.xml and choose this file in the next step, select Upload.
5. On the next page, select Everyone, Specific users/groups, or Just me to specify who the add-in is deployed to. Use the Search box to find specific users or groups. If you've deployed to just yourself, you can select Change who has access to add-in to deploy to more users later. Please, note that only users with installed Add-in will have signatures applied to emails after they are deployed.
A green tick appears when the add-in is deployed.
Please Note! Outlook add-ins can take up to 24 hours to be processed by Microsoft 365 and users might need to relaunch the Outlook app.
The minimum required version:
For Outlook on Mac is 16.54 (21101001), New Outlook mode.
For Outlook on Windows is 16.0.14511.10000.