Yes, the passenger details for each person travelling on every booking must be supplied.
We have recently revised our system so that all travellers have the option to store API for future use when you add a set of passenger details.
If you have a Frequent Traveller account, you now have the option of both storing your API in your My Eurotunnel Account ahead of making a booking, and also storing the details when you add API to a booking.
Please note we only require your API information for the Folkestone to Calais part of your journey. We do not require API information for the Calais to Folkestone part of a return trip, or trips that are Calais to Folkestone only.