Get bearer token - Expression.Error

Hi, 
I'm trying to get a bearer token from a API so that I can refresh it to get data. 

I have the following code, and it returns the token, but it also returns an error. Any idea what I'm missing?

Error:
Expression.Error: The field 'token' of the record wasn't found.

Code:

let
url = "https://myurl/authenticate",
headers = [#"Content-Type" = "application/json"],
postData = Json.FromValue([email="[email protected]",
password= "mypassword"]),
response = Web.Contents(
url,
[
Headers = headers,
Content = postData
]
),

Data=Json.Document(response),
access_token=Data[token]

in
access_token