RE: Outlook mac preview doesnt sync emails, fails to sync.

Please help us to confirm if you obtained the correct version based on the steps outlined on the article below. Look out for "Install Outlook for Mac for Office 365"

https://support.office.com/en-ca/article/Install-Office-using-Office-365-for-business-72977511-dfd1-4d8b-856f-405cfb76839c

Based on the subject, we would assume that you have installed the preview version that comes along with Office 2016 Mac Preview.