Adding email directory to contacts

Hi, I am a student with a microsoft email. I have a directory of students in Microsoft Webmail and I am looking to transfer all of the emails to my “contact” list at once, so I am able to export them. Microsoft is only allowing me to add them 1 by 1. Was wondering if anyone knows how to select all or if there’s an easier way to go about it.
CTRL+a and other keyboard commands like this do not work.
My end goal is the export all of the contacts.