How to handle "unsupported_grant_type" from laravel passport

I'm playing around with laravel and try to enable client credentials grant to secure some api endpoints.

To provide some context: I want to create an api that stands between a database and several websites (and SPAs). So I'll be able to do some monitoring (what website/SPA calls which ressources) and in general add some security. So in this case where no additional user inforamtion is required, the client credential grant for machine-to-machine communication should be the best approach.

I followed someone tutorials (e.g. this tutrial) to implement these grant type but I get stuck...

I did the following:

• load passport: composer require laravel/passport
• add service provider to config/app.php: Laravel\Passport\PassportServiceProvider::class,
• migrate: php artisan migrate
• install: php artisan passport:install
• added HasApiTokens to App\User.php
• added Passport::routes() to app/Providers/AuthServiceProvider.php
• last but not least set driver option of the authentication guard to passport in config/auth.php

So far so good. Now I created a sample client with php artisan passport:client:

New client created successfully.
Client ID: 3
Client secret: S5s9oEIRm5DNy5ySsr1H6jWlraOCZyF24gcpoDrJ

Now when I want to get a token for this client by using postman (added in the body.formdata like provided here)

I get the following error.

{
    "error": "unsupported_grant_type",
    "error_description": "The authorization grant type is not supported by the authorization server.",
    "hint": "Check that all required parameters have been provided",
    "message": "The authorization grant type is not supported by the authorization server."
}

Am I missing something? I thought I did all the necessary steps to register the grant type?

Thanks in advance!!

You misspelled grant_type. In the screenshot it says grand_type.