AppManager uses a standard REST API. You'll need to authenticate with your API key and set the correct content type for your requests.
Depending on your endpoint, you requests should look something like this:
curl -X GET \https://use.appmanager.io/api/v1/... \-H 'Authorization: Bearer 12g1823918273182d14hr4kk3j1j0a8e' \-H 'content-type: application/json'
You can retrieve your API key, by visiting your account section and then scrolling down to the "API Key" section.