Integrate OKTA (SAML) SSO into PHP application

General information for the website: Below
Description of requirements/features: We currently have a native PHP application with no frameworks which we need to integrate with OKTA for Single Sign On / SSO using SAML - below are links to the developer network in OKTA which detail what is involved etc.

http://developer.okta.com/use_cases/integrate_with_okta/

http://developer.okta.com/standards/SAML/

Use case is our customer is using OKTA for SSO and they also want to be able to use it for our application so they can sign on from OKTA without needing to remember additional username and password. That said, this should be developed in such a way that the SAML could be used for something other than OKTA in the future if required.

Plan to build this integration in your own environment / server and test and demonstrate this as we cannot give live, direct access to our servers or code.

You should as a minimum have good knowledge and experience of SAML and ideally of OKTA specifically.
Extra notes: