Indoor training apps such as MyWhoosh and Rouvy receive your LeCoach workouts the same way as every platform: through Intervals.icu.
Setup (one time)
Connect Intervals.icu to LeCoach in Settings - Integrations.
On the Intervals.icu connections page, connect the app (MyWhoosh, Rouvy, ...) and enable 'Upload planned workouts' and 'Download activities'.
After that, the push is fully automatic: your scheduled workout for the day shows up in the app's workout section, and your completed ride flows back to LeCoach, pairs with the plan and gets scored.
Workout not showing in the app?
Restart the app — most indoor apps fetch planned workouts at startup.
Check the workout is in your Intervals.icu calendar; if not, see sync troubleshooting.
Check 'Upload planned workouts' is enabled for that app on the connections page.
Keep your FTP in sync
Indoor apps run ERG mode against their own FTP setting. Keep the app's FTP equal to your LeCoach/Intervals.icu FTP so the absolute watt targets match what your plan intends.