How to make OAuth authentication and use Instagram API properly these days?

Question

I'm added as a developer into a FB and Instagram bussiness account. A bussiness has been fully verified, all the documents and settings have been set up. However, there haven't appeared Instagram app ID and secret anywhere. There're, however, an app_id and secret of Facebook in the dashboard.

I've tried to use them to authenticate via Instagram. It didn't work.

I open this url in the browser:

https://api.instagram.com/oauth/authorize?client_id=<my_app_id>&redirect_uri=http://localhost:8080/auth/instagram-oauth&response_type=codescope=user_profile,user_media

Then I enter my login/pass and then I get this error on an html page:

{
    "error_type": "OAuthException",
    "code": 400,
    "error_message": "Invalid platform app"
}

What's the matter? If I have to use Instagram app_id and secret, but where are they in the dashboard? There're only those of Facebook there, not of Instagram.

My goal is to authentificate at Instagram, in order to then be able to make API calls to Instagram from the server side.