This can happen for three reasons: 

  1. The workout builder & exercise tracking features are not activated on your account; Contact us to activate this feature.
  2. The Exercise option is not activated in your team's settings. To fix, open team settings-general settings, activate the Exercise button and save.
  3. Your exercise list is empty. To fix this issue, go to Settings, Exercise settings, add some exercises and workouts

This tutorial shows how to add exercises and workouts