Fetching data using api with key and api secret

I am all new to power bi and I want to connect to a online CRM application. I have created an api key and an api secret but I do not have any idea how I can get data from the api. Information about the api is can be found here https://developer.simplicate.com/explore.

I have searched the forum and I am able to connect to the api with the code below.

let
     apiUrl = "https://demo.simplicate.nl/",
     options = [Headers =[#"Authentication-Key"="xxxx", #"Authentication-Secret"="xxxx"]],
     result = Web.Contents(apiUrl , options),
    #"HTML-bestand geïmporteerd" = Web.Page(result)
in
    #"HTML-bestand geïmporteerd"

But when I change the apiURL to https://demo.simplicate.nl/api/v2crm/organisations I get the message my credentials are not valid.

Can anybody gif me any direction on how to add a new query that wil fetch all the organsations. If I have one example I am sure I am able to get started from there.

Kind Regards,