I had Express working fine, it would sync no problem. Then it stopped working for some reason. So I uninstalled it, and tried to do a fresh install and I keep getting an error message that tells me I can't install while Garmin Express is open. It isn't open because I no longer have it on my Mac. I trashed it correctly, and now I cannot install a fresh version of it. I'm going round in circles so grateful for any help.
I am sorry that you are having trouble with Express. If you are getting this message, the Garmin Express service is most likely still running in the background. Trashing the app will not stop the service from running. The easiest way to stop the service after trashing the app is to restart the Mac. Once the Mac is restarted you should be able to install the latest version of Express.