There is no free solution for this task. Neither the Mac version of Outlook nor the Windows version comes with an add-on facility for this task. There isn’t any freeware application as well that can help you at this. However, there are plenty of paid tools to convert OLM files to PST mail format. 

OLM to PST Converter Ultimate by Gladwev was much impressed with the conversion speed and accuracy. The tool converted my emails directly from the Outlook database. The tool offers free conversion of up to 10mails per folder. 

I am looking out for the easiest way to move from Outlook Mac to APple Mail. mine is a POP account and no email exists in the server. Please help me with this.

If you are stuck in the middle of a query of how to convert Zimbra to PST with all the Zimbra mailbox database, then you can try Zimbra to PST Converter. A remarkable and useful application to batch export Zimbra mails to Outlook PST format with attachments including contacts, notes, calendar, journals, briefcase and more in a single time. The software is easy to use and provides accurate result without any data modifcation. Preview is one of the main feature of the software which allows to view the Zimbra mail information before continuing with the final conversion. Download free Zimbra to PST Converter software edition to understand more about the working process.

To know more visit: http://www.cubexsoft.com/zimbra-export/pst