Retrieving External IdP Token

I was able to retrieve the external IdP Token of Stackoverflow and GitHub successfully. However when I make the API call:
GET /auth/realms/{realm}/broker/{provider_alias}/token HTTP/1.1
Host: localhost:8080
Authorization: Bearer <KEYCLOAK ACCESS TOKEN>
Specifically I make the API call to Stackoverflow like so:
I get the following response:
I have the following question about what to do next:

  1. What should I do with the access token?
  2. Do I need to decrypt the access token? If so what encryption is being used to encrypt it, base64 or something else?
  3. How do I see the details of the access token?
  4. Do I need to make another Stackoverflow call or Keycloak API call to using this access token as is, to get the details?

Any help would be much appreciated.

Thank you.