Mission Failed (Sierra 7)🔫

I've played this level 3 times and I keep loosing at the same spot I loose last time. Now I don't know why I keep loosing and just looking at that stage where I keep dying I believe no one can possibly get pass there with just the help of a gun, only very skilled players would pass and it would have to be a shotgun that would help one tap every enemy and to do that you have to kill them with at most 2 shots and every shot you take you must hide to also avoid getting shot.
If you feel like the using a shot gun would be stressful here is another tip I think should work, using lethal or grenades, you either use a flashbang or just use a grenade to blow all of them (I thought of this while writing this post). So normally I don't buy grenades in the game before going for a mission because I want to save money for health and now I'm dying rapidly, the money I could have used to but grenades after this idea has been spent on buying health which did not help me but I'd find away to get more money, maybe by watching ads just so I could buy atleast two grenades incase any other problem comes up. Thanks for visiting my post and do not forget to drop off your comments before leaving goodnight.