In the available authorization pop up, scroll to AUTHCODE section and input client ID and client secret values download while creating OAuth2.0 client registration instance. Clicking on Authorize button, will be redirect for login in a new tab. (login using any operator with access group PegaHC: Administrators).

On successful login, you should see Logout button in place of earlier Authorize button as shown below.

Now, close the popup and proceed to try any of the API’s.