Converting OLM (Outlook for Mac) files to PST (Outlook for Windows) manually involves several steps. Please note that this process might be a bit complex, and it's recommended to create backups of your OLM files and follow the steps carefully. Here's a general outline of the process:

Export Data from Outlook for Mac (OLM):

Open Outlook for Mac.
Click on "File" > "Export."
Choose "Outlook for Mac Data File (.olm)" and click "Next."
Select the items you want to export (emails, contacts, calendars, etc.).
Choose a location to save the OLM file and click "Save."
Transfer OLM File to Windows:

Transfer the OLM file you exported to your Windows PC using a USB drive, network, or cloud storage.
Import OLM File to Outlook for Windows:

Open Outlook for Windows.
Click on "File" > "Open & Export" > "Import/Export."
Choose "Import from another program or file" and click "Next."
Select "Outlook Data File (.pst)" and click "Next."
Browse and select the OLM file you transferred.
Choose the destination folder (usually your mailbox) and click "Next."
Optionally, choose to allow duplicates to be created or not.
Click "Finish" to start the import process.
Reorganize Data in Outlook for Windows:

After importing, you might need to reorganize the data in Outlook for Windows, as the folder structure might be different from the original Outlook for Mac setup.

Greetings,
Peter