New to PC gaming question about controller set up

[Rsinart]

Heya, so downloaded this the other day and been having fun with it. But honestly coming from being a console game my entire life, I am struggling using a keyboard and mouse. I can do it, but I am slow and my giant hands hit things and I mess up. Not sure thats the reason I can't seem to kill anyone or what lol.

But I got a pc controller and have it set up. But when I am using the left trigger to aim, and the right trigger to shoot. I can't seem to figure out how to set it up so I can keep aimed in and shoot at the same time. If I am aimed in and then press to shoot it takes away me looking down the sights.

Any info would be appreciated. Looks like a fun game even if I am terrible at it at this time.