I do import the organized ride's routes, but that's often not necessary, since the roads are usually well marked.

Exploring!
But the Garmin routes have made riding unfamiliar roads easy. For solo or smaller groups. I can ride a very complicated route, with lots of turns.

Stats
I originally got the Garmin for the maps, but I found I like the ride recordings, too. I can see where I went on a group ride. I get elevation and grade, time and distance info, and lots of other statistics. I have heart rate and cadence sensors.

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Downloading
Anyone can download the ridewithgps route, no membership needed. (Paid members get a few more options, like advance warning of turns on the .tcx route.)

Every ridewithgps route page has an Export tab at the top right. I click the TCX Course link to save the file.
On my Garmin 720, I plug it in via USB, then the Garmin shows like a flash drive. I just copy the .tcx route file from my Downloads folder to the Garmin's Courses folder.

The 820 appears to use the NewFiles folder instead. See the ridewithgps help for the 820 here.