The certificate request created in the previous step must be send to a CA. The CA is responsible to create a valid server certificate based on the information provided by the CSR.

Important: the certificate emitted by the CA must follow the PKCS#7 certificate chain format. The response file must contain the public key certificate of the ABAP server as well as the CA’s root certificate. SAP Help 🔗

The following screenshots are taking from my own CA.
Add an end entity for the server.
Submit CSR
Download certificate
Save as p12 (PKCS#7)

Result

You now have a P7B file that contains the signed certificate for the server in Baes64 format.