I’ve tried using the plugin in Lightroom with the setting “Use Graphics Processor” both enabled and disabled. In the guide it says to disable it. For me it seems to work fine either way. What’s the reason for the guide telling us to disable it exactly?
If you have the latest version of Lightroom Classic, you can enable the graphics card acceleration. The reason you couldn’t do this previously was because of a bug in Lightroom that caused some issues when the graphics acceleration was enabled and you were changing an image via a plugin.