Dated copies of the official program page and FAQ as read, confirmation of the official payment channel, records of the payment itself showing the recipient, and every acknowledgement received from the program. Keep records of any intermediary approach separately, including messages that quoted unofficial amounts.
A payment file that proves what was paid, to whom and on what terms
Because the program is new and its terms are published online, the applicant's own record of what the terms said on the day of payment is important. Save the official page and FAQ as dated PDFs, note the gift amount, processing fee, eligibility statements and family terms shown that day, and keep the executive order alongside. Record the payment channel exactly as the official site describes it and keep the bank confirmation showing the recipient, the amount and the date.
File every acknowledgement, reference number and subsequent communication from the program. If an intermediary offered to collect payment, keep those messages too; they may be needed to show that the applicant declined and paid only through the official channel. On the personal side, keep the passport, proof of Canadian citizenship, and any documents the program requests, such as background information for the applicant and each family member.
None of this replaces the records the builder's construction business will need in the destination state, which form a separate file.