Why am I getting authorization_code instead of access_token when using passport-facebook strategy

[shibichakkaravarthy]

I have follewed the steps mentioned in the documentation and still can't figure out what mistake I'm doing. Here is the code...

passport.use(
  "instagramFB",
  new FacebookStrategy(
    {
      clientID: FACEBOOK_APP_ID,
      clientSecret: FACEBOOK_APP_SECRET,
      callbackURL: "http://localhost:3000/instagram/accounts",
      profileFields: ["id", "displayName", "photos", "email"],
      scope: [
        "user_posts",
        "pages_read_engagement",
        "pages_manage_posts",
        "publish_video",
      ],
    },
    function (accessToken, _, profile, cb) {
      console.log("InstagramProfile", { profile, accessToken });
      return cb(null, { ...profile, accessToken });
    }
  )
);

passport.serializeUser(function (user, cb) {
  console.log("SERIALIZE", user);
  process.nextTick(function () {
    cb(null, { id: user.id, username: user.username, name: user.name });
  });
});

passport.deserializeUser(function (user, cb) {
  console.log("DESERIALIZE", user);
  process.nextTick(function () {
    return cb(null, user);
  });
});

// This is the endpoint called when fb login is invoked
export const instagramAuth = (req, res, next) => {
  passport.authenticate("instagramFB", {
    state: JSON.stringify({ userId: req.params.userId }),
    authType: "reauthenticate",
  })(req, res, next);
};

// This is the callback Endpoint
export const getConnectedAccounts = async (req, res) => {
  try {
    console.log("CALL BACK", req.user, req.query);

    res.status(200).json({ pages: "" });
  } catch (error) {
    console.log("error", error);
    res.json({ error });
  }
};

I'm supposed to get the access token and profile in req.user according to docs but it is undefined and I'm getting a "code" in req.query. Somebody please help me out with this...