Most users convert OLM to PST files in such a case. Because OLM is not compatible with Windows Outlook, and converting it to PST apparently gives a way through that. But I suggest taking a much better method. Try Vartika OLM to PST Converter. It can auto-load Outlook identities folders by itself. Naturally, this makes it a lot easier, but most importantly, it makes the conversion accurate safe. If data loss is your biggest concern, you should definitely try this one out. You can’t go wrong with OLM to PST Converter for Mac.