Hello, I can not download routes and segments from Strava to my Garmin 520 ... Asking for your help

If you're referring to courses, make sure you have the Strava connection enabled for courses under Account Information?

Then make sure you "star" the route on strava

Once that's done, go to Garmin Connect Courses and look for your course. It should be there with Strava as the source. Then you can send it to your Garmin device