New Zwift User having issues

Hello!  I’m hoping you all can help.  I am using an older MacBook, still in good condition.  I’ve updated all software and started a free-trial with Zwift.  Everytime I click ‘start ride’, the program closes and force quits.  Also, I can’t seem to figure out how to connect to my Garmin.  Any help or suggestions is very much appreciated!  

Have you uninstalled and re-downloaded?  After the unintall, search for “Zwift” in all your files, then Send to Trash, and Empty Trash.  Then do the re-install.

WRT connecting to your Garmin, that happens after you get past “Start Ride”