Export from Trasely
Open your route in Trasely, tap Export, then choose GPX. If Garmin Connect is not offered in the share sheet, tap Save to Files.
Use this for Forerunner, Fenix, Epix, Venu, Vivoactive, Instinct, and other Garmin watches that support Courses.
Export GPX in Trasely, import it into Garmin Connect as a Course, then send the Course to your watch.
Open your route in Trasely, tap Export, then choose GPX. If Garmin Connect is not offered in the share sheet, tap Save to Files.
Open Garmin Connect and go to Training & Planning → Courses. Choose Import, select the GPX file, pick the correct activity type, and save it as a Course.
Open the Course, tap Send to Device, select your watch, and sync Garmin Connect while the watch is nearby.
Reference: Garmin course import and send course to device.