Hello Renato,
You can integrate the OnPremise version of S4HANA with C4C only via PI.
But Cloud version is possible only via HCI . Below is the step by step process for 1602 release
https://websmp204.sap-ag.de/~sapidb/012002523100003564712016E/S4HANA_OP_C4C_1602_RDS.pdf
The 1605 guide is available at https://service.sap.com/bp-cfc-s4op
Also check if this can help you : SAP C4C sales integration with SAP S4 HANA | SCN
Regards,
Manideep Satya