Originally Posted by WhyFi

Once you connect to the PC via ANT stick, the files are typically saved to C:/Users/*Username*/AppData/Roaming/Garmin/Devices/XXXXXXXXX/Activities

It's a hidden location, so you'll have to unhide, but you can then upload the file manually on Strava (Strava and Garmin Connect have never played together nicely for me, so I've had to manually upload like this for a while).