The donation - which was legal and properly declared - came under fresh scrutiny earlier this year, raising questions about the influence of wealthy foreigners on domestic politics.
Electoral law does not allow foreign donations above $1500, but NZ-registered companies are considered local even if they're foreign-owned.
Mr McClay repeatedly insisted the two men never discussed the party donation while he was on his taxpayer-funded trip to China.
In response to an RNZ request, the ministry confirmed: "no mention of a donation was made at the meeting".
The meeting notes list several conversation topics including the horse-breeding industry, live race broadcasting, and the challenges doing business with New Zealand.
It also states: "Rider Horse has established branch office in Auckland".
Some sections of the email have been redacted to avoid prejudicing international relations or the commercial position of another party.
Two NZ officials attended the meeting on 12 July: the minister's private secretary Chris Langley and NZ Embassy deputy head David Evans.
Embassy staff and NZ Racing Board representatives were also in attendance at a separate reception later in the day along with Mr McClay and Mr Lang.
In August, Prime Minister Jacinda Ardern described the $150,000 donation as being "outside the spirit" of the law, but the National Party dismissed that, saying it was entirely above board.
Mr McClay said Mr Lang first indicated his NZ-based company wanted to support National during an encounter in his Rotorua electorate in 2017.
He later listened in to a phone call with Mr Lang and then-National MP Jami-Lee Ross to organise the donation.
RNZ's request under the OIA was delayed by 14 working days for "further review and consultation" and then another ten working days for "the final stages of processing".
