Solder a wire between the arcade button's two GND legs to connect them together. One leg is for the button and the other is for the button's LED.

Solder a wire from one of the button's GND legs to the QT Py's GND pin.

Solder a wire to the button's LED's anode.

Solder the LED anode's wire to the QT Py's pin A0.

Solder a wire to the button's input leg.

Solder the button's input wire to the QT Py's pin A1.