Starting with UPDD version 6.0.365 a 64 bit version of the Windows API is available below.
Select the download version that matches or is the closet to you driver version:
The zip file is a package containing all files needed by the API.
It should be extracted to any folder; but NOT the updd install folder.
Extracting to c:\program files (x86)\updd\x64api for example would be a good approach.
The important files are:
Which should be linked with your application as appropriate.
All other files are files used by Qt.