Yes, you can still use your existing version of Outlook as long as it's compatible with Office 365. We recommend using Outlook 2013 or greater, but we support from Outlook 2010. If your version of Outlook is older than 2010, please give us a call at (480) 463-8843.
If you already have Office, you can still use it after the upgrade. You'll also have access to the Office 365 features and software that are included with your plan.