Hey there, at this moment activities on Strava do not automatically sync to Garmin. The best option is to manually export your Strava activity and upload it to your Garmin Connect account.

Here is information for exporting your files from Strava: https://support.strava.com/hc/en-us/articles/216918437

Doing this with tcx files, Garmin does not accept them, saying "An unexpected error occurred while processing the file." It only seems to work with GPX files, but they in turn are missing loads of information. Has anyone been able to upload tcx files you get out of Strava?

Would also love to know how to make this happen - get the same error message. Drives me crazy that I can't get teh data into all one place on Connect! Any ideas?!

I had problems with my garmin watch and at that time I was running with my phone and Strava. I uploaded the workouts in tcx format without problems