How to configure SSO?

I read on the website that Mailbox supports integrating with existing SSO-providers. To be specific this is what this page says:
Interface

We offer connections that work with your IT systems, as well as single sign-on (SSO) solutions.

Which is awesome of course! We're running Authentik as our auth-provider and would love to integrate it with Mailbox so our employees can easily login everywhere with one account (SSO) including Mailbox. But I can't find any documentation or settings for it.