Deploying the Add-in for Outlook

Deploy the add-in to your users' Outlook mailboxes in the Microsoft 365 admin center.

On the Cloud App Security management console, go to Administration > Add-in for Outlook, and copy the Link to manifest file.
The link uploads the add-in in the Microsoft 365 admin center.
Log on to the Microsoft 365 admin center with your Global Administrator account.
Go to Settings > Integrated apps and click Upload custom apps.
On the Upload Apps to deploy screen, click Provide link to manifest file, paste the link you copied in step 1, and click Validate.
Wait until the validation is completed, click Next.
On the Add users screen, select an option under Assign users, and click Next.
Note:
This add-in works only for Exchange Online users protected by Cloud App Security.
On the Accept permissions requests screen, review the app permissions and capabilities, and click Next.
On the Review and finish deployment screen, review the information and click Finish deployment.
Wait a few minutes for the deployment to complete.
Click Done.
According to Microsoft, it can take up to 24 hours for a newly deployed add-in to appear on the app ribbon in your users' Outlook mailboxes. Your users may need to relaunch Office to view the add-in icon on the app ribbon.