If you want to convert MBOX to PST format, you can try an easy manaul trick that requires no paid software or any other cost. Via the manual trick shared in the blog post (linked below), you can move email messages and other mailbox data from Apple Mail to Windows Outlook.

Read this blog post for more information - wordpress.semnaitik.com/2014/05/24/convert-mbox-to-pst-manually/

I hope the shared information would be helpful here.

Thanks and best regards.