Host the above files under your app domain. Ensure that your web server can respond to:
https://<your_domain>/__/auth/handler
https://<your_domain>/__/auth/handler.js
https://<your_domain>/__/auth/experiments.js
https://<your_domain>/__/auth/iframe
https://<your_domain>/__/auth/iframe.js
We recommend downloading and syncing the files periodically to ensure that the latest bug fixes and features are picked up.