Cannot apply operator & to types Text and Function

Ha mschoenhub ,
that was a tricky one 🙂
In the function for the token, you are not returning the last step.
Please change it to this:

() =>
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