SlicerPyTorch uses the tool light-the-torch to choose a matching distribution. You could try using it yourself in Slicer’s python console and see if there’s a more informative error.
Or skip light-the-torch and copy the desried pip install command from here based on the cuda version, etc. that you want. Then in Slicer’s python console do
slicer.util.pip_install("<your pip install command>")
just omitting the initial “pip install” from the command string.