The topup airtime from the front page is for regular airtime top up, small discount is applied. 

While the Free Aitime event is about receive free Airtime via inviting friends download and use Kilimall APP.  

Once you have successfully invited over 5 friends(Showing from bottom right), you can withdraw by clicing the WITHDRAW BUTTON,  then enter amount you'd like to withdraw,  next, verify your phone no. and submit.