Things to add from a person who used ahk for a few things already (although im not a master yet). You can also create an ahk file by right-clicking and selecting new, where you normally make new folders. At least for me it showed the ahk script file as a option, the ".ahk" doesnt have to be added in that case. These also come with a few pre-written lines of code, which increase the speed and performance of the script (for only 4/8 keys its not that significant, but id still recommend it, bc it does some other stuff too). Also normally the ahk programm comes with am info file, which contains practically everything you would need to use ahk for other stuff!
Edit: I would advise to add "#SingleInstance force" at the beginning of the code, it prevents the script from being run multiple times at once. It terminates the old one when you start the file again