Hi, Rachel.
Our plugins use WordPress user profiles but we do not have access restrictions of our own. Your request sounds like a Single Sign On (SSO) sort of setup. You could probably find an existing plugin or do custom coding to bridge Outlook/Active Directory things with the WordPress login.
We actually do not have access controls for our calendar, but various WordPress membership plugins (or some pretty simple custom code) can usually restrict content based on URLs and/or Custom Post Types (of which we have 3: Events, Organizers, Venues).
By default, your logged in users would likely be Subscribers and therefore only be able to read posts (including our custom post type posts). You could upgrade specific users to be Contributors, Authors, Editors, etc.
It sounds like you might not be familiar with WordPress’ user roles so here’s a helpful reference: https://codex.wordpress.org/Roles_and_Capabilities
So, I’d say if you are using WordPress at all with your SSO setup, our calendar can likely do what you need it to do.
Last but not least, we have a pretty great Refund Policy so you can buy one or many of our add-ons and thoroughly test them.
I hope this info helps. Let me know if you have any follow-up questions.