Ann: Share Purchase Plan Offer Document, page-14

so, the company didnt do the greatest job in putting out dates in the first announcement but generally there should have been an ex date (i.e. 1 day before record date), therefore you would have needed to purchase shares on the 20th before the 21st to be considered a shareholder on the 21st, kinda how ex dividend works where you cant buy on the ex date and be entitled to dividend.