Hi @Madhu Muppavarapu ,
As the article said" Office Online Server only works with SharePoint web applications that use claims-based authentication":
https://learn.microsoft.com/en-us/officeonlineserver/office-online-server-overview#how-sharepoint-server-uses-office-online-server-for-viewing-and-editing-office-documents
You can check the Claims-based identity in SharePoint:
https://learn.microsoft.com/en-us/sharepoint/dev/general-development/claims-based-identity-in-sharepoint
Hope it's helpful.
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