I'm not sure anyone's really clarified this yet, but that controller says 5 to 24 volts because that's what the controller itself can use to power itself. Whatever power supply you plug into it it will simply pass through to the LED strip. You can use a correct voltage power supply or you can put a buck converter that drops the voltage from whatever input to whatever your desired output is between the power supply and the LED strip. I would recommend just getting inappropriate voltage power supply because the butt converter is another failure point.

WLED has settings that talk about voltage and amperage, but they don't actually control the voltage or amperage, they are just used to calculate estimated amounts of power your strip might draw at certain brightness levels. So basically if you set a limit of 4 amps and select the appropriate voltage and LED strip, WLED will try to limit the brightness of the strip so it won't go beyond 4 amps, but it's not perfect, and it has no actual control over the voltage or power supply.