Hi @David12529
The setting that allows instant bookings is called Instant Book, which one can turn on. However, this guest is already messaging you about a booking, instant book would just have made the transaction instant. I don't think this is what they want, they want to discuss something to do with pricing or payment before booking. If it's half price they want, you probably aren't keen.
They probably mean that they want to pay half now and half later? Is that how you also understand it?
Payment terms may be available for long bookings, but I would simply refer all payment issues to Airbnb. My advice: if you want this booking, tell the guest you'll approve it and put them in touch with customer service to discuss payment.
It's possible that they are not a serious booker and taking a chance because you're new - either way, a discussion between them and customer service will result in a booking or not, depending on whether they pay on Airbnb's terms.