My understanding is that Salesforce connections are REST API enabled, however for Authentication Using Stored Credentials (which is now being Deprecated) they used SOAP.

You can get more information about the extractor from the following link

https://docs.celonis.com/en/extractor-detail,-salesforce.html

Thanks @Abhishek Chaturvedi 

Yes..I'd seen that in the documentation but wasn't sure if for 'stored credentials' is it just the authentication that is SOAP based, or even the actual extraction too is SOAP based. Would you know?

Thanks !

Bhasker