I am trying to access Microsoft Bookings by using Rest API

I did this

xmlHttp = CREATEOBJECT("MSXML2.ServerXMLHTTP")
xmlHttp.open("GET", "https://graph.microsoft.com/beta/bookingBusinesses/{My_Unique_User_Identification}/services", null)
xmlHttp.setRequestHeader("Content-Type", "text/xml")
xmlHttp.send("")
result = xmlHttp.responseText


Those lines when executed gave me an error in result


ERROR

Code : Invalid authentication token
Message : Access token is empty

Perhaps there are other things to specify in order to get a token

And then with that token I should be able to query Bookings

Anyone can guide me to a solution?