To get them: 1 / registration and verification with the referral code. 2 / buy 250 euros in btc. 3 / you receive 15 euros in btc. 4 / you sell the 265 euros and withdraw them to your account.
To get the Luno 15€ / 15$ referral bonus, register with a referral link and trade for a minimum of 250€/$. You can buy and sell bitcoin several times until you reach the required turnover of 250€.