Simbrief is Navigraph now…technically speaking of course. OP needs a little more information. Is he trying to download the MSFS .pln (or whatever it is) from the simbrief website and saving it into a folder in MSFS file structure so he can load it into FMS that way and have ATC or whatever IDK. I have always wondered how you can input an external flight plan like for CRJ or CJ4 and have a IFR ATC with the default ATC in MSFS. I know 100% there are tutorials on youtube for this. I’ve just been lazy and not bothered to watch any yet.