Outlook on Android will connect to a Zimbra server using EAP Exchange Activesync Protocol:

Install Outlook from the Play Store and start the application. If no accounts were previously configured you will get this screen. Tap Get Started.

Fill in your entire email address and tap Continue.

Your phone will take a few seconds attempting to find your mail server/account. It may flash an option to setup manually and then it will go to this screen. Tap NOT OUTLOOK? then Change account provider.

Tap Exchange

Fill in your email account password and a descriptive name for the email account. Then slide the ADVANCED SETTINGS* switch to the right. Fill in Server with zimbra.virtualarchitects.com and Domain/Username** with your entire email address. Tap the check mark in the upper right corner of the screen.