This article explains why you cannot install Security Center if TLS 1.0 is disabled in Windows.
During the Security Center installation, when prompted to select an existing SQL database server, the installer attempts to connect to the specified server but cannot authenticate it if TLS 1.0 is disabled in Windows.
TLS 1.0 is disabled in Windows or you are using a more recent version of TLS. Only TLS 1.0 is supported.
Enable TLS 1.0 for the installation process.
This issue is resolved in Security Center 5.6 SR4.