To deploy the ZynBit add-in to all your users, you should install the plugin as the admin. Log into portal.office.com and open the Admin Center. Open the Exchange Admin Center from the Admin Centers drop down.
When the Exchange center opens, Add-ins is available under organization at the bottom right side of the screen.
Clicking Add-ins will bring up the menu where you can search for ZynBit from the Office Store (For Office 365 Customers). For Exchange 2013 and 2016 customers, scroll to the bottom of this article.
Click on the Office Store link and search for ZynBit.
Once the plugin is installed, you can set the plugin visibility as desired.
For Exchange 2013 and 2016 Customers Insert the URL by “Adding from URL”: http://outlook.zynbit.com/manifest-prod.xml