After installing CrewsControl you will see this
You must now go to Settings -> General -> Device Management and select Irons+Co llc then select trust in order for CrewsControl to run on your device.
We have been asked why isn't CrewsControl in the app store? Because Apple has told me twice that it is clearly an application designed for enterprise and not appropriate for the app store. Plus without having to wait approximately 10 days for an approval from Apple for updates, we can add new features and respond to issues very quickly.