Race won't start on Mac

[jbrit10]

Help! I'm not a coder, so I bought the complete OpenSprints kit a few years ago. We cancelled doing any gold sprints events due to covid and now that we want to do some events, the software isn't working.
The sensors light up and flash when the magnet passes, but the SilverSprints software just shows 0:00 for time and doesn't do anything when I click START.
I'm orking on a new Mac w/ OS12. When I follow the steps to upgrade the hardware (not even sure if this is necessary), I do not see the "Arduino/Genuino Uno" board as described.
Thanks in advance!