Hallo Jituda,
you mentioned that your DB is already installed on a different server but your Windows environment is not HA.
Hence my understanding is that you are implementing a distributed system (even if your DB is HA).
So your initial screen shot is correct:
Under Ditributed System select
1) "Install the SCS" to install the SCS
2) "Database Instance" to connect your SCS to the database
During the installation of the DB you should get a screen where you can tell the installation process the SID as well as the database host. Here you point your installation at the DB which has been installed on the remote host.
Regards
Thomas