Microsoft Single sign-on implementation on existing classic ASP.Net with application events (i.e, session, pre_requesthandler) already defined on global.asax

Question

Hi,

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• Existing App

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I have an existing ASP.NET application which is using NT authentication at the moment. The application is designed such that the authorization code is implemented in global.asax. Example, (1) application start is set with a list of actions like setting licenses, setting cache (2) session is added with timeouts and session variables (3) pre-request handles the authorization whether the user has access to application.
App is non-MVC, classic asp.Net application and hosted on IIS

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• Requirement:

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The requirement is to move away from NT authentication to Microsoft AD SSO authentication.

Problem:
All the Azure Active directory implementation examples (link) that I am looking at has implementation for Single Page application, ASp.Net Core, ASP.NET MVC, web api etc.

Could anyone please help me in pointing to the right code samples where I can modify my current application and integrate the AAD authentication?