Automated test on CI Newman and Auth0 without client_credentials

Iā€™m currently implementing API testing on a project.
This project is linked to Auth0.
So thereā€™s an APP (SPA format) which is protected by the Auth0 Management API via authentication.
However, everything Iā€™ve been able to find on forums, tutorials, etc., concerns the possibility of authenticating with the type: client_credentials
But the API manager doesnā€™t allow this functionality on the APP in question, the box is grayed out and so I canā€™t activate it.

(Moreover, in the ā€œTestā€ onget of Auth0ā€™s API manager, when I select the API concerned, I receive this message:
Error! grant type ā€˜client_credentialsā€™ not allowed for the client.

So, Iā€™ve managed to use autentication in postman with Autentication on the Oauth2 choice (and fill in everything I need, Callback url, Url, Client ID, Client Secret, scope, and even the audiance that is required), it works, but I need to fill in the login/password fields in a window that opens.

I need to find the right system allowing me to play these Postman collections in Newman, and therefore not have the user input system.

I canā€™t find an example that describes how to do this workflow, the code, the pre-script or any other help to point me in the right direction.

Iā€™d like to thank in advance anyone who can spare the time to help me.
Have a nice day.