@Pavitra Chauhan Thanks for reaching out. It sounds like you have invited a guest account to the Azure Entra ID tenant and then granted that user access to the FHIR server. Logging in a guest user to Entra ID may require multi-factor authentication (MFA), which is an additional layer of security that requires users to provide two or more forms of authentication to access a resource.
As an alternative solution for enabling read-only access to the FHIR service for Google accounts, is to use Azure AD B2C. Azure AD B2C is a cloud identity service that allows you to customize and control how users sign up, sign in, and manage their profiles when using your applications. It supports social identity providers such as Google, Facebook, and Microsoft accounts, as well as enterprise identity providers such as Azure AD.
However, setting up Azure AD B2C can be an involved process, but it allows for more direct login of Google or other retail accounts to the FHIR service.
do let me know incase of further queries, I would be happy to assist you.