I don't use TrainingPeaks, but do have a basic account. Checking TrainingPeaks site.
How to Sync Garmin Connect With TrainingPeaks – TrainingPeaks Help Center
SYNCING WORKOUTS FROM TRAININGPEAKS TO GARMIN CONNECT
Once you have linked your Garmin Connect and TrainingPeaks accounts, the next 15 days of eligible structured workouts on your TrainingPeaks calendar will immediately sync to your Garmin Connect calendar.
A Garmin Connect icon on the workout Quick View in TrainingPeaks indicates that the workout has been synced to Garmin Connect.
The next time your Garmin device syncs with Garmin Connect, your TrainingPeaks workout will be sent to your device. Depending on the model of your Garmin device, your workouts will sync by Bluetooth, WiFi, LTE, USB cable, or ANT+ Stick. Find more information about getting your workout from your Garmin Connect Calendar to your Garmin device here.