The SmartDelay feature enables a pass request for you plus one companion on Premium plan, or three companions on Metal. The Ultra plan enables unlimited free access to the lounges regardless if a flight is delayed or not. However, Ultra customers will need to purchase passes for companion(s), available in the Revolut app.
Get your SmartDelay pass by going Lifestyle → Travel → Smart Delay.
Once you get it, the SmartDelay pass can be used for 36 hours from the time it's issued (based on UK local time) at the origin airport. Depending on where you are in the world when your lounge pass is issued, you may have more than 48 hours or less than 48 hours to redeem your lounge pass (the minimum validity period for a lounge pass is 36 hours).
Lounge passes are non-transferable, this means they can only be used by cardholders and companions who experienced flight delays of one hour or more, as long as they registered the flight at least two hours before the originally scheduled departure time, and have received a free lounge pass.