Cannot apply operator & to types Text and Function

Dear all, 

I am trying to use a bearer token which I get from a function in a query.

Function: 

() =>
let
    // Get the API Token
    api_url = "https://api.xxxxxxx.com",
    token_path = "/oauth2/access_token",
    ClientID = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", 
    Secret = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", 

    EncodedCredentials = "Basic " & Binary.ToText(Text.ToBinary(ClientID & ":" & Secret), BinaryEncoding.Base64),

    Token_Response = Json.Document(Web.Contents(api_url,
    [
        RelativePath = token_path,
        Headers = [#"Content-Type"="application/x-www-form-urlencoded",#"Authorization"=EncodedCredentials],
        Content=Text.ToBinary("grant_type=client_credentials")
    ]
    )
    ),

    // Get the token from the API response
    token = Token_Response[access_token]

in
   Token_Response

Query: 

let
api_url = "https://api.xxxxxx.com",
path = "/data/v2/libraryEntries",
fields = "all",

Data = Json.Document(Web.Contents(api_url,
[
    RelativePath = path,
    Headers = [#"Authorization"="Bearer " &#"GET Access Token",#"Content-Type"="application/json"]
    ] )),
    #"Converted to Table" = Record.ToTable(Data),
    Value = #"Converted to Table"{2}[Value],
    #"Converted to Table1" = Table.FromList(Value, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
    #"Expanded Column1" = Table.ExpandRecordColumn(#"Converted to Table1", "Column1", {"id", "questions", "answer", "languageCode", "creator", "lastUpdatedBy", "createdDate", "lastUpdatedDate", "lastReviewedDate", "lastReviewedBy", "libraryEntryOwner", "inlineImages", "status", "tags", "scores", "location", "attachmentCount"}, {"id", "questions", "answer", "languageCode", "creator", "lastUpdatedBy", "createdDate", "lastUpdatedDate", "lastReviewedDate", "lastReviewedBy", "libraryEntryOwner", "inlineImages", "status", "tags", "scores", "location", "attachmentCount"}),
    #"Expanded lastReviewedBy" = Table.ExpandRecordColumn(#"Expanded Column1", "lastReviewedBy", {"id", "name"}, {"id.1", "name"})
in
    #"Expanded lastReviewedBy"

The query throws the following error:

I got this from the following tutorial https://www.myonlinetraininghub.com/connecting-to-an-oauth-api-like-paypal-with-power-query where it seems to work. Can someone help me please?