The probability of Aya being offered a coupon on at least one of the six days she visits the website is 100% minus the probability that she is not offered a coupon on any of the six days, which is described by a binomial probability with zero successes in six trials with a probability of succes p = 0.15.
The probability that Aya will be offered a coupon on at least one of the days she visits the website is 62.29%.