If your Mac OS X version is 10.13 (High Sierra) or lower, just download and install the network driver and the serial driver from beagleoard.org.

If your Mac OS X version is higher 10.13 (e.g. Mac os X Catalina), there is no possibility to get Ethernet access via usb.

The network driver offers Ethernet over the USB access and the serial driver offers USB to UART conversion.

After you have installed these two drivers reboot your computer and open the Network Panel of the System Preferences app. Now, connect your device (e.g. a BeagleBone Black) to the USB plug of your Macintosh.

In case of the BeagleBone Black, boot with the Bootkey passed. Release the Bootkey. After a schort time, you will see 2 additional interfaces called BeagleBone Black in the Network Panel (see fig. 1).