FYI: if you 'pre-loaded' Microsoft Flight Simulator it's just the client

If you downloaded the Microsoft Flight Simulator pre-load expecting to dive straight into the game at launch, well: take a seat. The pre-load only downloads the game’s client, which weighed in at a suspiciously tiny 532.5MB. Once the client is downloaded, you’ll have a 91GB download awaiting.

Of course, if you purchased the game on Steam you weren’t given the option to pre-load anything, so add the client size to that launch download. If you purchased it on the Microsoft Store and did do the preload, you may have been observant enough to notice that the download was a) very quick and b) very small. If that’s you, well done.