Another approach that may work a bit more reliably uses clipboard in a folder. It uses the same Send key technique for desktop. But inside a folder, select one folder with the mouse and hit the hotkey. It should only try to create instructions.txt if the highlighted item is a folder. Since that creates the file inside the folder, I use Run to launch it. Might save opening the selected folder and hunting for the file. Since it uses FileAppend function, if the file already exists in the folder, it should open it. You can spiff up the code a bit by doing stuff like saving clipboard contents and restoring etc... This is just a working skeleton.
#IfWinActive ahk_group DeskGroup
if (class = "Progman") or (class = "WorkerW")
else if (class = "CabinetWClass") Or (class = "ExploreWClass")
ff = %Clipboard%
ff := ff "\instructions.txt"
return DllCall("psapi.dll\EmptyWorkingSet", "UInt", -1)