Microsoft OAuth 2.0 Authorize endpoint complains about missing secret

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I am trying to create an online meeting with a web application using the Microsoft Graph API.

When I try to initiate an authorization request to get permissions from the end-user to create a token with a similar URL to:

https://login.live.com/oauth20_authorize.srf?state=xxx&scope=https%3A%2F%2Fgraph.microsoft.com%2F.default&response_type=code&approval_prompt=auto&client_id=xxx

I get the following error message from the Microsoft API:

The client does not have a secret configured. If you are the client application developer, configure a secret through the application management site at https://go.microsoft.com/fwlink/?linkid=2083908.

I have a secret configured for the application in the "Certificates & secrets" part under the "Client secrets":

I have no clue what I am missing here and the Microsoft documentation is not really helpful.