for IOS 9 user:
How to trust Enterprise apps on iPhone or iPad
Step 1: Click install and wait installation progress done.
Step 2: Launch Settings from your Home Screen.
Step 3: Tap on General.
Step 4: Tap on Profiles/Device Management."
Step 5: Tap the "Lucky8 Technology Inc.""
Step 6: Tap trust "Lucky8 Technology Inc."
Step 7: Tap to trust
Step 8: Completed.