I got the same error but didn’t have a flightsim package to delete. I tried renaming roaming, then it started but wanted a 163GB download… ugh ■■■■■■ made this game. google earth has much more data, it’s a 500kB app, starts instantly without the idiotic pause music and gets all the data live. which can be cached locally to not waste bandwidth. instead you opted for 100GB download so the houses could all look soviet era. And the cities could look like mudscapes. You had one job 
but on the plus side the flight model was hopelessly sluggish/laggy so after overpaying for the game and the 6 hour install, I plaid it once in dismay and barely played it since. sigh.
And I’m a computer scientist, I’ve coded d3d with pixel shaders, nice high res large scale terrain, I’ve worked with terrain data, I know a little bit about it.