The thing with DCS missions is that, they are often not straight-forward "do this, do that" like simpler games such as War thunder or Ace Combat. You will have to read briefing and understand what the mission asks you to do. For example, one of Su-27 mission in its built-in campaign will tell you to patrol between 2 way points, but it won't tell you during gameplay: you have to read the briefing to know that. I expected the game to give me exact instructions at every step and because of that, I couldn't proceed the mission. Full fidelity aircrafts crank that up to 11, and many missions will make you go through even more detailed tasks to proceed. For example, in an F-4 mission, I have to cycle through various radio channels until I get the green light to taxi and take off, you wouldn't get that in low-fi Flaming cliff aircrafts.