If Duet on the iPad says "Launching Duet" or "Adjusting Resolution" for more than a handful of seconds, this is most commonly a timeout error.
You can refresh the start of a connection by rotating the device, quitting the iOS app and relaunching Duet on your device, unplugging the iPad or iPhone cable and then plugging it back in or quitting the Mac app and relaunching it.
If that doesn't work try opening System Preferences > Displays > Arrangements while the iPad is showing "Launching Duet" and toggling the Mirror Displays checkbox On then Off again.
If you are still having issues connecting reliably, please contact us at firstname.lastname@example.org and include your Mac's System Profile so we can take a closer look!
This probably means the installation did not complete successfully. Please uninstall Duet Display and restart your PC. Then download a new app installer .exe from duetdisplay.com/windows and install again. Make sure to restart your PC to complete the installation.
If you are still having issues connecting reliably, please contact us at email@example.com and provide us with a DxDiag so we can provide step by step instructions to diagnose and fix.