I used both the USB connection and the USB stick. SM1 had no WiFi interface so I cannot tell you about that aspect. The Lightburn software generates files with a .gc filetype. If you want these files to work with SM1, you must change the filetype to .nc.
I made the somewhat painful decision not to buy another Snapmaker and have now purchased a Shapeoko machine. I am currently putting it together now. I had not been on the SM forum for a while and it was only that I saw your e-mail message. I managed to miss the message from @jlropes so the information should help. remember to set the baud rate to 115,200 or there will be no communication between SM and Lightburn. Their forum is super handy too and the developer’s are always ready to help out. I left a link to my brief look at Lightburn. It is unfinished because I am not impressed by the rudeness of SM staff and their abject failure to address issues raised for years.