acquire more than entitlement offer? additional shares

hi, does anyone know about this options on entitlement offer booklet? execpet the offer shares,, you can acquire a little more ?

i think it means,you could acquire additional shares but less than your entitlement offer shares ?
also your acquire additional shares may failed or not pass
base on is any other people give up their rights.

but should we pay these extra additional shares first ? wiating refund if failed ?

Thanks