Check that you have the latest version of the app on your Edge? You will need to use Garmin Express to do that.
The new Strava/Garmin course integration is designed to replace using this app, but it should still work.
You don't have to install Strava Routes for getting routes from Strava to your Edge so don't bother with that app.
Connect Garmin and Strava and allow routes. Then create the route in Strava and mark it with a star. Sync your device and you will get the routes on the device.
Read more here: https://support.strava.com/hc/en-us/articles/115000919304--Syncing-Strava-Routes-to-your-Garmin-Device