Hi Andre,
Thanks for the quick response.
Yes, I have assigned the correct role as per the document.

Also the secret is correct too.
FYI,
I added my user to the Finance and operations instance and assigned a "system admin" role, and then it started working, but when i try to access it without my user account(i.e., Interactive user who is trying to make the call from cds) in finance, it is not working.

When iam trying to access data with s2s app user, it is not working.
Any interactive user of Microsoft Power Platform who tries to access finance and operations data through a virtual entity must also exist as a user in finance and operations. Therefore, technically, not all users have to be users in finance and operations. Only those users who access finance and operations data through virtual entities must be users in finance and operations.(Working)
A S2S application user can also be used to call into virtual entities. For this kind of integration, the application user must be set up in System administration > Setup > Configure Azure Active Directory Applications. This allows for applications to integrate with finance and operations using virtual entities.(Not Working).
Do we need to create all the Interactive users in finace and operations to access data/virtual entities from Finance and operations?
Regards,