If you want to export OLM file in Outlook 2016 then, you need to be aware about the fact that your Outlook should be updated. If it is not updated, You will not be able to see Export button.
In spite of updated Outlook 2016, Export button is not visible
-- View for Export in Outlook File Menu.
-- Select Export button from Tools tab.
If you are very much conscious about loosing your data. So, You want to archive your MAC Outlook data i.e. .olm file as a backup. To export OLM in Outlook 2011, there are multiple options available as per your need. You can export emails, contacts, attachments, calendars, tasks, appointments and notes in MAC Outlook.
In case you want to archive OLM file data from Outlook 2011, then you can follow the given steps:
-- Go to File >> Export