OLM files cannot be opened directly in Windows Outlook because Outlook for Windows only supports PST files. To resolve this issue, you can use PDS OLM to PST Converter, which converts OLM files into PST format quickly and safely. Once converted, the PST file can be easily imported into Outlook on Windows systems.

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