You can also check if the device have the “Developer Mode” activated, in case your device haven’t it enabled you need access to an Apple computer with XCode installed.
To check it open Settings and search for a Developer options (not sure about the option name in english) in the main screen
Steps to activate with an Apple computer:
- Open XCode
- Open Windows > Devices and Organizator
- Connect your device to the computer and the activation proccess starts instantly.
- During the proccess you see a wheel next to your device name, when the wheel dissapears the process is done
- Check the iDevice Settings if the Developer options appears now.