You can review the first video from this post titled ‘Device Setup’.
Or simply click the ‘Device’ button in the lower-left of the ‘Laser’ window. then select to create a profile ‘Manually’. Select Ruida, complete the remaining screens, hitting ‘Next’ until you complete all screens, then select the ‘Finish’ button. This will then try to establish a connection with the laser and will report the status of this connection and what you are connected to at the bottom-center section of the LightBurn window.
When you say, " I hope I don’t have to completely rework all of the files I created in the GCode version of Lightburn . . .", you should consider that these files were tuned to provide settings for a different system with different power (watts) and mechanical capabilities. Yes, you will need to make changes to the existing library of GCode files to run them correctly on the Ruida system. You will have a different range of power settings and will be able to drive the new system at different speeds than you were able to with the K40. “Completely rework” is a bit dramatic, but you will need to adjust the appropriate settings to fully benefit from all advantages the new gear provides.