Below error show when try to install SSLVPN client on Mac OS High Sierra due to Mac OS is not allowing the KEXT:
/opt/sslvpn-plus/naclient/signed_kext/tap.kext failed to load - (libkern/kext) system policy prevents loading; check the system/kernel logs for errors or try kextutil(8).
Error: Could not load /opt/sslvpn-plus/naclient/signed_kext/tap.kext
installer[4571] : install:didFailWithError:Error Domain=PKInstallErrorDomain Code=112 "An error occurred while running scripts from the package “naclient.pkg”." UserInfo={NSFilePath=./postinstall, NSURL=file:///naclient.pkg, PKInstallPackageIdentifier=com.vmware.sslvpn, NSLocalizedDescription=An error occurred while running scripts from the package “naclient.pkg”.}
installer[4571] : Install failed: The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.
installer: The install failed (The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.)
Workaround
Add tun tap team-id to pre-approved kext list.
Step 1: Uninstall any partially installed sslvpn-plus client.
Step 2: Boot Mac OS in recovery mode.
Step 3: On top bar click on utilities > terminal.
Step 4: Add tuntap kext team id
to pre-approved list with the following command:
spctl kext-consent add KS8XL6T9FZ
Step 5: Reboot Mac OS to normal mode.
Step 6: Verify if Team-ID is seen in kext approved list with following command:
spctl kext-consent list
Step 7: Install SSLVPN Client package.
Reference
VMware Knowledge Base: Unable to install SSLVPN client on Mac OS High Sierra (59190)