ACK requires you to press F10 to exit some menus, and CTRL + various function keys can change the DOSBox environment ACK runs in (to increase and decrease its speed, for example). On newer Mac laptops, the function keys are by default mapped to hardware functions, so in that case you will need to hold down Fn + F10 to get ACK to register that you’ve pressed F10. You will also need to hold down Fn to use DOSBox’s function key controls — for instance, to slow down cpu cycles, you will need to hold down Fn + CTRL + F11.
If you want to use the function keys in ACK and DOSBox without having to hold down Fn, launch OS X System Preferences, go to the Mouse & Keyboard menu, and check the box that reads ‘Use F1-F12 Keys to control software features.’ Note that after doing this, pressing Fn + F1 – F12 will control hardware features, and you can uncheck the box to revert to standard function key behavior at any time.
Also note that FN + down arrow is PageDn, FN + up arrow is PageUp, which is needed to scroll some menus.