To convert an OLM file into PST format, I would like to share a manual trick here that will help you import your OLM files data to Windows Outlook. Follow the steps given below:
1. Create an IMAP mail account and setup it with Outlook for Mac.
2. Now synchronize your IMAP mail account and Outlook for Mac.
3. Move emails and all other mailbox items from OLM file to the IMAP mailbox folder.
4. More all the data from the IMAP mailbox folder to the Windows Outlook.
You can read more about manual tricks search Migrateemails.com blog in Google.