This was an automatic, not a manual, install so the paths are set by the installer? I checked after installation and the 64bit library path contained the VCL UI Pack 64bit directory so had been added correctly.
I have now installed on a second system, with the exact same error. I then uninstalled and tried the 13.0.8.0 installation (my previous VCL UI Pack installation was a few versions lower) - this produced the same error.
What effect the error is having I can't determine - the AdvTouchKeyboard gets installed and appears to be working OK.