Sso with nextjs

Question

I want make a Single Sign On, where when I access my dashboard.sunize.com.br if there isn't a access_token, I will be redirected to sso.sunize.com.br and I will be authenticated and save my access and refresh in the cookies from sso.sunize.com.br, so I will be redirected to dashboard.sunize.com.br and I will ask to sso.sunize.com.br API for get the cookies with the access token, but the saved tokens do not come. This is my sso.sunize.com.br API route:

import { cookies } from "next/headers";

 export async function GET(req: Request) {
  const Cookies = cookies();

  console.log("all cookies:", Cookies.getAll());
  return Response.json({ tokens: Cookies.getAll() });
}

  export async function POST(request: Request) {
  const res = await request.json();
  cookies().set("at", res.at);
  return Response.json({ at: res.at });
  }

I need that the token that I saved in sso.sunize.com.br become when I make a request from dashboard.sunize.com.br for this token.