I had a look at the form from the NSW Govt’s web site.

 Is the ‘Total amount last determined for that financial year only and for the whole strata or for the lot involved?

The Total amount is determined by whatever period you specify on the form.  The form has boxes for you to enter dates “Period” ___ “to” ___.  It is for the lot involved because you specify the lot at the top of the form.

is the ‘Amount (if any) outstanding’ and ‘Amount (if any) in credit’
for the whole strata for that financial year only or the balance in the bank account or
for the lot involved only for the Admin/Capital Works funds –

The amount should be for the lot specified at the top of the form.  Not the whole strata.  It is not the balance of the bank account.  You have to show whether the lot owner has fallen behind in levy payments.

Outstanding means that they owe money to the owners corporation.

Amount in credit is the opposite.  The lot owner has paid for a future period outside the dates you specified.  You put the administrative fund levy amounts in question 3 and the capital works fund levy amounts in question 4.

if it is for the lot involved, does ‘Amount (if any) in credit’ mean that the lot owner has already paid their annual levy or what?

No.  It means they have paid for a future levy which has not been invoiced yet.  For example, if your financial period is 1 July 2025 to 30 June 2026 and all the levies are paid, there is $0 outstanding.  If they have also paid levy for 1 July 2026 to 30 September 2026 (which is outside the financial period), then you put that amount in the credit.  If a levy is due on 1 July 2026 and the lot owner deposited the money on 30 June 2026, that amount is in credit.