When you'll launch the app for the first time, your iPhone will display an alert "Untrusted Enterprise Developer ". This is because the app is not installed through the App Store.
You must ask your iPhone to trust Stuart in order to use the application. This is a simple process:
- Go to the Settings of your iPhone
- Tap on General
- Tap on Profiles & Devices management
- Tap on Stuart
- Tap on Trust "Stuart"