As others have said, make sure it's actually in your path
echo $PATH
If it's not, move it to one of the directories, or run it explicitly from where it is. I just downloaded it. It saved to my ~/Downloads folder. I had to chmod +x egctl-linux-x86_64, then run it from a terminal with ~/Downloads/egctl-linux-x86_64 and it worked. Although I don't have that mouse so "working" for me is Error: device not found (VID:0x3367 PID:0x1978). is the mouse plugged in?