Is there a way to convert an MS Store purchase to a Steam key? I was finally down to under 5GB to download last night and thought I would be able to fly today. This morning when I restarted to installer which had of course crashed again overnight it said I had 57GB to go 
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It is ridiculous that the installer isn’t even stable nearly a week after release. I think that even starting from scratch with a Steam download I would get to use the sim sooner than if I keep using the Store installer.
I don’t know of any way to do this but what makes you think Steam would be any better? The only difference of the Steam version is it puts some files in a different location but once you start the game the process of downloading everything I believe is the same so there is no guarantee that Steam would be any different.
Of course it might work but people have had it fail through Steam as well. Since MS don’t seem to know what is causing it the only guaranteed way is to wait for a fix.
You can try requesting a refund from the MS store and then purchasing on steam. You should note, though, the MS store and Steam version use the same installer.
If your having issues, I would read through some of the troubleshooting guides which have been posted around the interweb.
I don´t think this is possible because these are two different companys and both want to earn money 
at least I don´t know any game where it would be possible
Oh - thanks. I hoped the Steam version would use the Steam loader, which is pretty reliable.
The Steam installer just downloads around 1GB of data and then the rest is done the same way.
The installer is the same, buying on Steam won’t change anything. It doesn’t download / install the game through steam.
Another strange and unfortunate design decision.