Hello Anne,
The following document explains in detail the setup and configuration for S/4 HANA integration. This is published in the SAP Service Marketplace (SMP) and you will need login access to SMP to access this document.
INTEGRATION: SAP S/4 HANA and SAP Cloud for Customer via HCI
https://websmp205.sap-ag.de/~sapidb/012002523100016658232015E/S4HANA_C4C_1511.pdf
Best regards,
Sailaja