What type of information does SAML exchange between an IDP and Slack?

SAML, which stands for Security Assertion Markup Language, is primarily used for single sign-on (SSO) scenarios, allowing users to authenticate across different platforms without needing to log in multiple times. When SAML exchanges information between an Identity Provider (IDP) and Slack, it focuses on authentication and authorization details.

This means that when a user tries to access Slack, the IDP confirms the user’s identity through a SAML assertion, which contains necessary information such as the user's credentials and permissions. The assertion allows Slack to verify who the user is and what level of access they should have based on their role or group affiliation within the organization.

In contrast, the other options provided do not pertain to the core functionality of SAML. Billing information, user activity logs, and general metadata are not part of the authentication and authorization process that SAML is designed to facilitate. Thus, the function of SAML is accurately represented by the emphasis on authentication and authorization as it encapsulates the essence of what the SAML exchange aims to achieve in integrations with platforms like Slack.