Strava not installing on Apple Watch - fixed

How to fix when Strava app won't load onto Apple Watch?

This worked for me. I shut down and restarted my iPhone 12+, then connected it physically to my MacBook Pro via a lightning USB cable. A message came up on my iPhone for me to confirm I trust this device. Yes.

With the Apple Watch on its charger, I went into the Apple-Watch app on my I-Phone. In the My watch screen I scrolled down to Strava and clicked install. It took a while, maybe 10 minutes, but eventually a message came up on the App saying Strava is installed on Apple Watch. I don't know if all of these steps are necessary but this is what I did, and it worked.