How to get Music-user-token for apple music in nodejs

Question

I am creating a React-Native application with Nodejs on backend. My app has a feature to link apple music account with my app. for this, I need to have Music-user-token of particular user who has joined my app and for Music-user-token, I need user's permissions which ultimately requires user's login.

I created login URL for apple on backend and return it to frontend and the whole flow on authentication is working file but at the end, the access token I get on redirectUrl (which is again an endpoint on my server), has not permissions to access user's data from apple music platform.

I skim through the documentation of apple music api, but I got confused there.

I want to ask, How to get Music-user-token (either from front-end or backend) or as a backend-developer How can I create login URL for Apple music.

Regards

I tried to create apple login flow in NodeJS which is working fine. but access token has not privileges for user's apple music data.

Apple-Music api library

Note: Developer token is working fine and I created it like following:

export const appleDeveloperToken = async (
  req: Request,
  res: Response,
  next: NextFunction
) => {
  try {
    const options: any = {
      algorithm: "ES256",
      expiresIn: "180d",
      issuer: teamId,
      header: { alg: "ES256", kid: keyId },
    };

    const jwtToken = jwt.sign({}, privateKey, options);
    res.locals.token = jwtToken;
    console.log("Developer token ", jwtToken);
    next();
  } catch (err: any) {
    next(err);
  }
};