ArcGIS Portal Active Directory Role based Permissions. Add AD roles to ArcGIS Enterprise and assign ArcGIS permission based on those AD roles.

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Configure a SAML-compliant identity provider with a portal—Portal for ArcGIS | Documentation for Arc...

Portal authentication configuration—Portal for ArcGIS | Documentation for ArcGIS Enterprise

you can also create groups in the portal that leverage the existing Active Directory, LDAP, or SAML groups in your identity store. Also, organization-specific accounts can be added in bulk from the Active Directory, LDAP, or SAML groups in your organization. When members sign in to the portal, access to content, items, and data is controlled by the membership rules defined in the Active Directory, LDAP, or SAML group. The management of group membership is completely external to the portal.

Create groups—Portal for ArcGIS | Documentation for ArcGIS Enterprise
Link Active Directory, LDAP, or SAML groups from an IdP

Add members to your portal—Portal for ArcGIS | Documentation for ArcGIS Enterprise

Add members from AD or LDAP identity providers

If your portal has been configured with an organization-specific identity provider based on Active Directory (AD) or Lightweight Directory Access Protocol (LDAP), organization-specific accounts can be added individually, in bulk, or from AD or LDAP groups managed by the identity provider.