Copy the downloaded .nex file to the SD card from your ZX Spectrum Next.

To launch the game, select it via the ZX Spectrum Next's browser.

To use a joystick, connect it to the left port.

If using a regular joystick, configure "left joy" as "kemps1"

If using a Megadrive gamepad, configure "left joy"as "MD 1"

That's it.