Zwift routes to Garmin Connect

Hi!

I have found info on the different routes i Zwift and you can download them as Strava segments. However I use Garmin Connect (GC) and would very much like to have theese routes as courses in GC but I have no idea how to “convert” from Strava segment to GC course. 

Can somebody please explain how to do that without having to buy any third party software.

Thanks

/Joakim