Integrate single page app into external platform

We already have a detailed single page application. This has been deployed in a production environment for a while. The current project involves integrating our web application into an external platform. The external platform has its own logging mechanism, user information, device information, and ability integrate third party applications like ours. Goal is to do SSO and integrate our web application into the platform. There are additional APIs that the platform provides. These APIs need to be integrated to extract other relevant user information and add on to the features that our application already provides.