According to your description, you want to integrate SSRS with Azure Active Directive so that users can authenticate with Azure AD credentials and have those credentials recognized by SSRS for authorization/permissions, right?
Based on my research, SSRS is currently not supported for Azure AD authentication. Currently we can only use Azure AD user/password for SSRS setting advanced connectivity options and using the driver .NET 4.6 (or higher). For more details,
Authenticating SSRS with Azure Active Directory
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