This is done through Intervals:
Connect Intervals.icu in LeCoach on Settings - Integrations
Verify that you have connected your Garmin, Wahoo or other account to Intervals on their connections page
On that page, make sure to select 'Upload planned workouts' to sync (LeCoach) workouts from Intervals to your Garmin, Wahoo, Coros, Suunto, Hammerhead etc device and/or to Zwift, MyWhoosh, Rouvy etc.
Now your workouts will be synced to the platforms you select. This includes the full structured workout including step targets.