Starting with macOS 10.13 (High Sierra), Apple has added a new security feature that prevents third-party kernel extensions from loading without specific user authorization. For more information about this from Apple, please see TN2459.
Specifically, when the Hilo-Thunderbolt is first plugged in, you should see two entries in the System Information panel. The first under Thunderbolt, LT-TB should appear:
The second under PCI, pci1621,14 "Audio" should appear:
This is the LT-TB installed in the Hilo. Since no driver is loaded yet, the driver hasn't had a chance to rename the PCI device to Hilo.
After the driver has been installed successfully, the pci1621,14 should change to Hilo.
To install the driver completely, first open the Lynx_OSX.pkg that was downloaded from the www.lynxstudio.com web site. After the driver installs, you should receive a message that a Kernel Extension has been blocked. Go into the Security & Privacy of the Systems Preferences pane, and click "Allow" for the Lynx Studio Technology extension. Once you restart your system the driver should load properly.