Their findings: more than 1,300 Trump condos were sold, not by people, but to shell companies where there was no mortgage and the real buyers's identities were secret. These accounted for more than a fifth of the Trump properties sold.
Why does this matter? The answer is simple: this looks exactly like transactions masking money laundering.
The article quotes a Treasury Department advisory about transactions like this: "Drug traffickers, corrupt officials, money launderers, and other criminals seek to exploit real estate transactions to hide their illicit profits, conceal their identities, and launder funds" (details here).
Almost certainly Robert Mueller and his prosecutors are looking into this as part of their criminal investigation othe President and his associates. The media has widely reported about how he specifically hired some of the best money laundering prosecutors in the country.
Hopefully we'll hear a lot more about this as shoes continue to drop.