Got it, and the display as well
"The only trick is: install.exe of the AlphaCool driver package doesn't work properly, so you have to manually install the driver using Device Manager."
Well, at first I installed alphaLCD_1.0.4.48_beta.exe in W7x64 with the display already attached. The driverinstaller that was automatically started (after installing the software) ended up freezing so I killed it using the task manager. After reconnecting the display and starting the Alphacool software, it works , didn't have to install the driver manually at all. Then I fired up a virtualized Windows 10x64, executed alphaLCD_1.0.4.48_beta.exe as admin (to prevend issues), which finished without problems. After that I connected the display to the virtualized W10, started the Alphacool software and....
Since that works, AIDA64 should be able to use it without problems, although I haven't tried that yet.
(Ignore the computername and username, never thought of changing those after upgrading W8.1 to W10...)