The Garmin watch can pick up data from any Stryd. You can set up the watch to pick up power from just your own Stryd. This is helpful if you run with other people that also have a Stryd.
1. First, you need to figure out the ANT ID from your Stryd. You can find the ANT ID on your Garmin watch. (check this article if you are not finding FP-xxxx on your watch).
2. You can enter the ANT ID using Garmin Connect Mobile on your phone (you can do the same with Garmin Express on the computer). Select your watch, and got Activities, Apps and More -> Data fields -> Settings). Note that menu names vary a bit from watch to watch.