Hi @Satheesh , External identities like Google and FB are "external providers" which means you'll be using B2B, which is not the same as B2C pricing. This page details the costs of using B2B.
To answer your question, you would need a Premium subscription to use external providers, so this would not be included with your free B2C subscription. Please let me know if you have any questions. If you need more detailed information about billing you could also open a free billing support ticket.
If this question helped you please mark it as "Verified" so other users can reference it.
Thank you,
James