I want to consider that Org ID and email attribute should be unique

For example

Org ID | Email
123 | moshontong@gmail.com
123 | moshontong@gmail.com

Now this throws an error, 123 | moshontong@gmail.com is duplicate. But if this is the case

Org ID | Email
123 | moshontong@gmail.com
021 | moshontong@gmail.com

OR
Org ID | Email
123 | moshontong@gmail.com
123 | joshontong@gmail.com

This is still a unique data since the ORg ID or the Email are not the same to other that

Is this your custom collection?

yes

If you want org Id to be unique, create a unique index on org Id. Same with email

so what if I have moshontong email on two document but the org ids is not the same does it still throws an error?

Since the org ids are different the unique constraint will not apply. Both documents will be regarded as distinct.

This only applies if you create 1 unique index with both attributes.

If you have 1 index on email, no 2 document can have the same email

Yes, I'm aware of that 👍