Switch on drone, then once it's done it's little musical interlude, push and hold the same power button until it bleeps once.
Then turn on remote, at the same time push and hold right shoulder function (the button below the photo one), the Fn button on the top (to the right of the sports mode button) and the pause button (to the left of the sport button), continue holding for a few seconds until the light on the top left of the controller flashes green at the same time as it bleeps, give it a few seconds and the green flashing light will go solid, that's it, their synced/paired.