SAML login callback when using IDP initiated, for auth0-react

I see this instruction when using lock.js to enable app to support the post back that SAML does after SSO login

But this does not apply to the auth0-react setup I have apparently. I am not sure what to do when I am using auth0-react. We got SP initiated login to work fine but IDP initiated fails after we try to redirect to these request/response flows:

  1. https://oururl/login/callback?connection=:white_check_mark:

  2. https://oururl/authorize/resume?state=***’ :white_check_mark:

  3. POST https://oururl/ :x:

So, as of now the callback happens after SSO SAML, then step 3 fails as 405 method not allowed because my application likely is not ready to handle this POST callback

So what do I do in my auth0-react app to fix step 3?

Any ideas anyone? Is this just not supported in auth0-react?