Clio Sync can't sync directly with an Exchange server, but if you configure your Outlook to store a local copy of your information in an Offline Storage Table (OST) file, you're all set. Setting this up is a bit outside our wheelhouse here at Clio, but here are some resources that should help:
Introduction to Outlook Data Files (.pst and ost) - this is a Microsoft article introducing the two types of files that can be used to store Outlook information locally.
Turn on Cached Exchange Mode - also from Microsoft, this article discusses how to enable (or disable) Cached Exchange Mode. Cached Exchange Mode must be enabled to store a local OST file, so if you'd like to use Clio Sync in an Exchange environment you'll have to enable it.
The ability to toggle Cached Exchange Mode is controlled by the administrator of your Exchange server, so if you run into any issues enabling this mode please contact your Exchange administrator.