Can a SAAS customer behind the portal use a third party integration/connector that uses the REST API?
There are two reasons why this third party connector should not be used.
1. The connector is using the REST API which is not compatible with Federated SSO. Because ;the customer is behind the portal they are using Federated SSO.
2. The REST API is not supported for customer use at this time.
Both of these are documented in our REST API Guides.