How do I get access to SAP S/4 HANA Cloud public edition (SAAS) as a SAP Partner?

Hello,

I need to get access to SAP S/4 HANA Cloud public edition (SAAS) in order to test CMIS (please see SAP_COM_0597).

So far I have not been able to find out how / through which agreement with SAP I can get access.
Anyone know help?

Thank you and kind regards

Katharina