Go to Settings > My Profile > from this page, you will find the places to click to integrate the tools.

NOTE: With the 2 way email integration, emails will show when the emails are between the person with their email integrated and the contact. 

This may present a risk after the contact becomes a client, as confidential emails between both parties can be seen by other people. Which could constitute a breach in confidentiality.

NOTE: You do not need to integrate the 2 way email sync in order to connect your calendar. You can do one or the other, or both. Whatever is preferred and best for your organization.

To view integrations for your calendar and email (Outlook, iCloud, and Google) go to Settings > My Profile

To view all other integrations, go to Settings > My Profile