Please note that the import/export function is currently not available in new Outlook for Mac. If you use New Outlook on Mac, we recommend using Apple Mail to copy and move emails between accounts as a workaround. You can also use Apple Mail to copy, export and import your calendar data.
You can only export Mac Outlook items as an .olm file, which can only be imported into Outlook on Mac, or with third-party software if it’s on another app.
Learn more about how to import/export/archive all your files in Outlook for Mac.