Thank you for posting your question. To consider your Application as Confidential, it must follow the guidelines of confidential apps:
Confidential applications can hold credentials in a secure way without exposing them to unauthorized parties. They require a trusted backend server to store the secret(s).
Grant types
Confidential applications use a trusted backend server and can use grant types that require specifying their Client ID and Client Secret (or alternative registered credentials) for authentication when calling the Auth0 Authentication API Get Token endpoint. Confidential applications can use Client Secret Post, Client Secret Basic, or Private Key JWT authentication methods.