The shares are issued for free (Nil Cost)Using a cashless...

The shares are issued for free (Nil Cost)
Using a cashless exercise mechanism
So the total amount issued is a percentage
See example below of previous issue taken from annual report 2019

Shares issued to Key Management Personnel on exercise of compensation optionsOn 25 October 2018,7,075,000 options were exercised by Directors using the cashless exercise mechanism as part of Stavely’s Employee Incentive Plan. On exercise of the options, the Company issued 2,808,892 shares. The number of shares was determined by the value calculated between the market price of the shares (based on a VWAP for the 5 trading days prior to the exercise date) of 31.51 cents and the exercise price of 19 cents in relation to the options.

So above you see 7,075,000 options exercised
But only 2,808,892 shares issued
Its calculated using the percentage difference of the (VWAP = 31.51) & the (EXERCISE PRICE = 19.0)
Which is 39.701682006%
So 39.701682006% of 7,075,000 options = 2,808,892 shares issued (My Actual Result 2,808,894) (2 shares difference)
Simple LOL