Google calendar freebusy api call

Hi there, I’m trying to call freebusy api(Freebusy: query  |  Google Calendar  |  Google for Developers) by using api connector but experiencing 401 error.
Can anyone advise me on this?

Currently, already completed basic auth set-up and can call Create calendar event but can’t call freebusy api.
This is how I set the api call in API connector.