Ive been trying the same strat as the world record to at least get a decent time and i just don't hit , like im trying as hard as i can to replicate it their is alway's something that goas south, someone know a guide ? or can explain me what to do ?

Sorry for late reply, you may have better luck asking in one of the discords in the future.

The world record strat for Patient Zero SA/SO is pretty difficult, but it's hard to suggest anything without footage of your own gameplay to compare.

I would suggest starting out with the 42 second strat first:

The 34s strat does mostly the same thing, but it uses a more difficult entrance into the building, as well as more precise kills on both targets.