Libre3 app won't scan

My cat is diabetic and the vet recommended a Freestyle Libre sensor for monitoring. They installed the sensor, but I can't get the app to take a reading.

Confusingly, there are several Libre apps currently in Google Play; LibreLink, Libre 1, Libre 2, and Libre 3. After trying all of them, I found that only Libre 3 app would even attempt to read the sensor. But when I attempt to do this, I only get a message about needing it 60 minutes for calibration. I've tried scanning probably a dozen times over a 12-hour period and always get the same result.

I'm getting frustrated. This app is complete garbage. All I need it to do is scan the freaking sensor and display the reading.

Does anyone have a suggestion? Maybe there's another app compatible with the sensor that actually works?