The Add-Ins for Outlook window will open in your browser
Select My add-ins
In the Custom Add-ins section, select Add a custom add-in, then choose Add from file
Select the XML file you downloaded in step 1
Select Install to install the add-in
The add-in will now appear in both Outlook on the web and Outlook desktop app
Open any email and look for the "Log to CRM" button in the ribbon!
Note: Installing custom add-ins from an XML file is currently only available through the Add-Ins for Outlook dialog using the link above. Once installed via the web, it will automatically appear in your desktop Outlook app.