Thanks, it's definitely not supposed to be easy, but you can make it out, there's a little scene at the end.
Characters at the doors have some tips, and with one of them you can even unlock a shortcut to make it easier.
But it's totally possible to do it the whole way. I think the clues from characters might be a little unintuitive, when they say "side to side" it's meant to be interpreted from one side of the street to another, not strafing A-D during a run.
So once you're behind cover - pick the next cover that is most perpendicular to the street and just book it in the straight line. If you think about it from snipers view, the less you're running towards him the harder it is for him to hit you. This tactic will work 100% of the time, there's no luck involved.