Ann: Notice of Annual General Meeting/Proxy Form, page-152

Pro, it might be a bit simplistic but the way I view it Paul was offered 4,000,000 shares @ $0.143 per share, unfortunately he was strapped and went to TNG (the Bank) and borrowed the money to pay for these share at NO interest, so yes we lose the interest on $572,000..
Now when the due date came around to repay the loan he again was strapped so he asked for an extension of time to repay the loan as can be seen in the 2020 Annual report.
5.2.5 Modification of terms of equity-settled share-based payment transactions On 26 November 2014, the Company granted 4,000,000 Plan Shares to Mr Paul Burton at a purchase price of $0.143 with repayment date on 27 November 2019, being five years from the date of issue of the Plan Shares, unless earlier repayment was otherwise required under the terms of the TNG Employee Share Plan.At the 2019 Annual General Meeting held on 18 November 2019, shareholder approval under section 208(1) of the Corporations Act 2001 was sought and received to extend the Repayment Date of Mr Paul Burton’s Plan Shares by four years to 27 November 2023.

So my take is, right or wrong Paul Burton will need to pay TNG $572,000 no later then 27th Nov.2023, so start saving your pennies Paul you're not getting another extension.
I have not found any record of that loan ever being paid back.