Hi @ajbily !
Were you able to move forward with your SAML integration?
I went ahead and also consulted our SAML engineering team - and the RelayState has to be provided by SP along with the request to the Identity Provider Login URL . The exact string (URL decoded) will be returned as RelayState with the SAML response.
Suppose the application has the Identity Provider Login URL: https://test.local.dev.auth0.com/samlp/3h9qAQsqC4H9Uhhj4MnYiq3kkaG2qPYe
If the request made to Auth0 is
https://test.local.dev.auth0.com/samlp/3h9qAQsqC4H9Uhhj4MnYiq3kkaG2qPYe?RelayState=https%3A%2F%2Fsso.ringcentral.com%2Fsp%2FACS.saml2
The returned response will be
*SAMLResponse: <encoded string>
*RelayState: https://sso.ringcentral.com/sp/ACS.saml2*
My advice would be to try with the https://sso.ringcentral.com/sp/ACS.saml2 as the RelayState and have this URL set as the Allowed Callback URLs in your Auth0 tenant → Applications → ringcentral → Settings → Allowed Callback URLs.
Hope this helps! Your feedback would be appreciated!