1. When you open a manually installed enterprise app for the first time, you will see a notification that the developer of the app is not trusted on the device. You can turn off this message, but you won't be able to open the app.

2. Click "Settings" > "General" > "Description Files" or "Description Files and Device Management". Below the "Enterprise Apps" heading, you'll see the developer's profile.

3. Click the name of the developer profile under the heading "Enterprise Apps" to build trust for this developer.

4. According to the prompt information in the pop-up box, click "Trust". Return to the phone desktop, and you can access the 68 App normally.