Unfortunately, this is on my brother's Dell, and he somehow lost his BeamNG folder by installing it in a weird location. Download time has improved to 3 hours.
It was a folder created by the new updater. Anyway, in your case just run the updater, wait for it until it creates the folder ''alpha_prerace'', and then close it, copy all the files of the game inside that new folder, and run the updater again. The updater should identify all the files and only download the ones that need updating, so total download will be 450-500 mb or so.
Go to your BeamNG folder and there should be a .txt file called 'serial'. At first I wasn't sure if it was put in manually by me, but I saw an SS of someone else with it.
the updater uses torrent technology (so the more people who download and leave there updater running so it can seed, the faster the download gets)
G̶o̶ ̶t̶o̶ ̶y̶o̶u̶r̶ ̶e̶m̶a̶i̶l̶ ̶t̶o̶ ̶f̶i̶n̶d̶ ̶y̶o̶u̶r̶ ̶p̶u̶r̶c̶h̶a̶s̶e̶ ̶c̶o̶d̶e̶,̶ ̶t̶h̶e̶n̶ ̶c̶o̶p̶y̶ ̶t̶h̶a̶t̶ ̶c̶o̶d̶e̶ ̶a̶n̶d̶ ̶g̶o̶ ̶t̶o̶ s̶e̶t̶t̶i̶n̶g̶s̶ ̶>̶ ̶Y̶o̶u̶r̶ ̶O̶r̶d̶e̶r̶s̶ ̶>̶ ̶L̶a̶s̶t̶ ̶O̶r̶d̶e̶r̶ P̶a̶s̶t̶e̶ ̶t̶h̶e̶ ̶c̶o̶d̶e̶ ̶i̶n̶ ̶t̶h̶e̶ ̶b̶o̶x̶,̶ ̶a̶n̶d̶ ̶p̶u̶t̶ ̶i̶n̶ ̶t̶h̶e̶ ̶e̶m̶a̶i̶l̶ ̶a̶d̶d̶r̶e̶s̶s̶ ̶y̶o̶u̶ ̶p̶u̶r̶c̶h̶a̶s̶e̶d̶ ̶t̶h̶e̶ ̶g̶a̶m̶e̶ ̶w̶i̶t̶h̶.̶ ̶A̶f̶t̶e̶r̶ ̶t̶h̶a̶t̶,̶ ̶t̶h̶e̶ ̶g̶a̶m̶e̶ ̶c̶o̶d̶e̶ ̶i̶s̶ ̶i̶n̶ ̶a̶ ̶g̶r̶e̶e̶n̶ ̶b̶o̶x̶.̶ Or...just do it the easy way I didn't know about. ._.
Done D seeding right now! Everybody, make sure you seed(keep uploading after the download is done) so the rest of us get better a download speed!!
lol wut's seeding EDIT- oh. that's what. I'm just gonna play Minecraft while this is seeding. It's taking forever