Thank you for reaching out about downloading a track to your Garmin device. It is possible to do so! If you navigate to the full trail page online, you'll notice that in small green text under the trail name, and the consensus ratings, there is an option for "Getting There," "Downloading the GPX File," and "Print". The Download the GPX File icon is an arrow pointing down into what appears to be a tray.
Once you've downloaded the file to your desktop or downloads folder, you can connect your Garmin device. From there, all you have to do is transfer the .gpx file from your desktop or downloads to the Garmin, and you should be ready to go!
Let me know if you have any other questions, or need any clarification. Thanks for a great question!