(reinstall the elicencer software to fix that error - google is your friend here)
you are over complicating it 
REMOVE from “studio setup” in nuendo
then UNINSTALL the EUcontrol software as I mentioned above - remove EVERYTHING (did I say to do that ?)
reboot
install with ONLY THE FIRST OPTION selected as I mentioned previously - it even says “CONTROL” on that option to give you a clue - do not install workstation !!!
then when it reboots (again) is should ask you to update firmware - you don’t have any avid stuff to update so just ignore - and set not to remind you again
it then asks to configure what devices you have - add your avid control app here, it obviously needs to be running for you PC to see it.
IF YOU DON’T GET THE AUTOMATIC CONFIGURE OPTION when you boot then then look in the window notification area there is an EUcontrol icon where you can add your AVID CONTROL APP
If there is anything you are unclear about then ask - but just randomly messing about and guessing isn’t going to fix it - just follow the instructions without adding random bits
ps there is also a windows control panel item if you want to configure mackie control - won’t need this with nuendo