In Outlook click on File – Manage Add-Ins
Search for Calendly for Outlook and click Add
Click Continue on the Privacy Policy
Choose whether you want to Pin the app or not.
From your Outlook application click on All Apps in your Ribbon menu
Click Add Apps
Search for Calendly then click on the tile
Click Open
Click OK to start using Calendly
Create a new email, and you should now see Calendly as an option in your Ribbon menu. If you don’t see Calendly listed, click the small arrow to expand the menu.