It is tricky, I rage quitted during the tutorial after a few failures
However once you get the controls down - awsd + space for the left code and mouse + left button for the right code. The mouse control is a bit sketchy but you don't have to keep moving the mouse to move the code, put the cursor near the bottom of the screen to move down, right edge of screen to move right etc. That's the first hurdle.
Then you just have to look for the static alphanumeric codes on the grid and move each of your codes over them and lock them in place.
Time does run out quickly so when the timer bar gets right near the end click abort and the alarm won't sound, you can just have another go, although the static code positions on the grid will change.
I tend to look for a static code first, if I don't find one within about 3 seconds I hit abort and try again. If it takes much longer you probably won't have time to move the matching code onto it, find the second static code and then moving the corresponding code onto the grid.
When you level you can put a couple of ranks into sabotage which will increase the time limit for hacking. You can put more ranks into sabotage so you get to use EMP grenades after a couple more level ups, they apparently give you access to computers just by detonating them.
It's one of those things that just 'clicks' after you succeed at it a couple of times, don't give up! Although don't torture yourself if you keep failing, give your eyes a rest then come back
