Install OWA Office 365 Button

Here are the steps to complete inside your Microsoft account Admin center.

1. Go to Microsoft 365 Admin Center> Settings> Services & add-ins > Click + Deploy Add-in. 
   If you are unsure how to access you can use this link https://admin.microsoft.com/ or, if you're already signed in, select the app launcher, and choose Admin.
   1. If you can not find this option click here to learn more: Begin deploying add-ins via the Services and Add-ins page in the Microsoft 365 admin center or via cmdlets for Centralized Deployment. https://docs.microsoft.com/en-us/office365/enterprise/use-the-centralized-deployment-powershell-cmdlets-to-manage-add-ins
2. This will open the Centralized Deployment side-bar > Click Next> Choose I have the manifest file (.xml) on these devices. > Browse for the XML file (downloaded in this step ) > Next > Choose which group you would like to deploy the OWA to > Deploy Now
   1. ACCESS XML FILE HERE
3. The Add-in will now appear in the add-ins list and will be available for all users. Select the Report as Phishing add-in > click Edit
4. Choose this option from the following:
   1. Fixed (default) The add-in will be automatically deployed to the assigned users and they will not be able to remove it from their ribbon