Zoho CRM and Office 365

I'm having a problem getting office365 integration fully working. I have followed the instructions located here: https://www.zoho.com/crm/help/office365/ and have the ability to invite users. However, there is no calendar sync integration active (following these instructions: https://www.zoho.com/crm/help/office365/#Office365_Calendar). There is no "Microsoft" under Extension & APIs in the menu. Is this integration limited to certain levels of services? This link says it's available at all levels ( https://www.zoho.com/crm/help/erutaef321.html#office-365).

Any assistance would be appreciated.

Thanks in advance..