As we all know, Mac Outlook generates the OLM format to store its data, whereas Windows Outlook generates the PST format. And many users want to use the free methods to convert their Mac OLM files into PST. I suggest those users try the OLM to PST Converter (DataRepairTools). In this method, you just need to set up an IMAP server account through Gmail in order to convert an OLM file to a free PST file.
To try this free methods, you can visit: https://www.datarepairtools.com/blog/methods-to-convert-olm-to-pst-file/