Okay so a workaround that I've managed to figure out with the help of @Horobol on twitter is to create a folder called "bin" in the same folder where you placed the PNGTuber+ executable, and then rename the "libgdexample.linux.template_release.x86_64.so" file to "libgdexample.linux.template_debug.x86_64.so" and move it to the "bin" folder. That should get it working for now, as long as you run it as root.
If it still doesn't respond to keyboard inputs, you might want to have a look at other peripherals connected to your pc that it could be picking up on instead. For me instead of my keyboard it was picking up the hotkeys on my drawing tablet.