If you want to convert Mac Outlook OLM files into PST format, PDS OLM to PST Converter
 is a simple and effective solution. The software helps users migrate Outlook for Mac mailbox data into Outlook for Windows PST format without losing emails, attachments, contacts, calendars, or folder structure.

The tool supports Outlook for Mac 2011, 2016, 2019, and Office 365 accounts. It also allows users to preview mailbox data before starting the conversion process.

https://www.perfectdatasolutions.com/en/olm/olm-to-pst-converter.html