Office 365: Export your contacts from Outlook on the web

Outlook on the web looks like this:

To export your contacts from Outlook on the web, you need to use Outlook on your desktop, which looks like something like this with a “File” in the top left corner:

When you add your Office 365 email account to Outlook on your desktop, Outlook on your desktop will sync with Outlook on the web. You can then export your contacts from your desktop to a file. You can use Outlook 2007, 2010, 2013, or 2016 to export your contacts.

To export your Office 365 email contacts:

1. Add your Office 365 email account to Outlook desktop.
2. Export your contacts from whatever desktop version of Outlook you have.

Credit : https://support.office.com/en-US/article/Export-contacts-from-Outlook-10f09abd-643c-4495-bb80-543714eca73f