I emailed Iberia about the terms. They emailed me back a complete list of terms..

Hereby, we attached all the conditions for you to consider:

¿ On-line purchases must be made through Iberia's website
¿ Purchase date must be between June 21st and June 24th, 2018.
¿ 9,000 Avios will be credited per ticket ONLY under the name of the Iberia Plus cardholder within 10 days after purchasing.
¿ Promotion is valid up to a maximum of 10 tickets per person (Maximum 90,000 Avios bonus per customer).
¿ Your Iberia Plus number MUST be included during the booking process and before the purchase is completed and tickets are issued.
¿ All flights must be operated by airlines within the Iberia Group (Iberia, Iberia Express or Air Nostrum).
¿ No time limit for your departure date, one way and round trip tickets allowed (No Avios redemption fares).
¿ Avios earned with this promotion will expire on December 1st, 2018. If Avios collected from this promotion are not redeemed before that date, they will be deducted from the account.
¿ If any of the tickets gets REFUNDED, the corresponding 9,000 bonus will be automatically CANCELLED.

My Iberia number was included AT THE TIME of booking, but later I went back and mysterious it was not included. I wonder if that's gonna create issue for me...