The last version to officially support Windows XP was Wavelab 6. If you buy Wavelab Elements 9.5, you’ll also be able to use Wavelab Essential 6 which you can download here:
You’ll have to contact Steinberg Support if you want a Wavelab LE download link.
I’ve got an OEM license (supplied with a Zoom recorder).
I tried to contact Steinberg support but because I couldn’t install Wavelab 9.5 and register it I had no registered products and couldn’t proceed!