After installing the APP, please follow the steps below to trust the developer, otherwise D-Back will not work

Step 1. First, click the Download button to install.

Download

Step 2. Go to Stettings > General > VPN & Device Management.

Step 3. Then find the untrusted apps in the ENTERPRISE APPS.

Step 4. click "Trust".

Step 5. Finally, click Trust the developer.

Download in progress.

Please check your Home Screen.