2. Click Get it now
Follow the wizard and it will link your email address using OpenID Mapping to Zoho (to check goto accounts.zoho.com or accounts.zoho.eu, Preferences, Linked Accounts)

OpenID Mapping: OpenID Connect is a simple identity layer on top of the OAuth 2.0 protocol, which allows computing clients to verify the identity of an end-user based on the authentication performed by an authorization server, as well as to obtain basic profile information about the end-user in an interoperable and REST-like manner.
You'll get prompted by Zoho to link and log into Zoho CRM. Once you log into Zoho CRM it will associate Office365 to Zoho CRM.
Do the same again, to enable the Event & Contact Sync. There will be no Zoho prompt, and it should take you straight into your Zoho CRM.
Once logged into Zoho CRM the 2nd time, go to SETUP|MARKETPLACE|MICROSOFT. You can now click the buttons Enable to sync Events & Contacts