When opening an app for the first time and attempting to grant access you may see this message:
"Your app isn’t verified"
Unfortunately Google will only authorise single instance applications, as Better Scheduling is copied for each installation this makes verifying the application impossible. But you are able to proceed.
Proceeding through the app verification if you're prompted
click the "Advanced" link in the lower left-hand corner
then select the "Go to Better Scheduling (unsafe)" link in the lower left-hand corner (Our application is perfectly safe and no information is sent outside of your domain).