POST request to /continue throws CORS

According to docs we need to make POST request if we want to pass data back to Auth0 after a redirect in the Action.

But it throws CORS when I do so.

     * @param token {string}
     * @returns {?object}
     * @throws {Exception} 401 or 500
    async resumeLoginFlow(token) {
      const url = `https://${AUTH0_DOMAIN}/continue?state=${this.stateToken}`;
      return await this.$, {
        headers: {
          Accept: 'application/json',

The error is:

Access to XMLHttpRequest at ‘’ from origin 'https://’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: No ‘Access-Control-Allow-Origin’ header is present on the requested resource.

I read this post but didn’t know exactly what needs to be implemented as a POST request can’t be a browser redirect.