If you see the message "External Editor preset creation failed" when attempting to use the Connect to Lightroom command in PixelSugar, it's likely that you're using Lightroom CC, not Lightroom Classic. Lightroom CC (the newer, cloud-based editor) doesn't support external editors at all. The original Lightroom (now called Lightroom Classic) is the only Lightroom that you can use with PixelSugar.
What Can I Do About It?
With Lightroom CC, we recommend a workflow where you process photos first in Lightroom CC, then export to a Folder and work with your images in PixelSugar.