To get the most out of iFile on iOS 9.3.5, you must first jailbreak your device. Jailbreak Tool
To help you get started with the setup, would you like the for the essential fixes or a guide on how to re-jailbreak with Phoenix if it expires? ifile ipa ios 935 work
Go to Settings > General > Device Management and trust your Apple ID profile. To get the most out of iFile on iOS 9