Formally, the minister is asking the government to seek what is known as an "unexplained-wealth order" which would compel Trump to provide proof of the funding source. When evoked, this is a legal requirement used to combat suspected money laundering.
If Trump refuses, then the government can seize the property in question.
The matter has now passed to the First Minister to decide how to proceed. The First Minister is the equivalent of a prime minister.
As a partly antonymous state incorporated within Great Britain, Scotland has exclusive control over decisions on this matter. This means Trump could not apply political pressure on the British Prime Minister, because the latter is powerless to stop a Scots unexplained-wealth order. And Trump is decidedly unliked in Scotland, too, so all the more incentive to get this ball rolling.