My impression at the time was that it was a Democrat witchhunt designed to make Donald J Trump look bad.

OK, the operation of the charities could have been "crisper". That is, there were many Trump-related entities: Donald J Trump, the Trump golf course business, Eric Trump, Donald's Foundation and Eric's Foundation. If one of the foundations bought anything from the Trump business that was called theft and corruption. Trump employees and other people connected to Trump ran the foundations so it all got a bit cnfused.

This is what Trump said:

The sleazy New York Democrats, and their now disgraced (and run out of town) A.G. Eric Schneiderman, are doing everything they can to sue me on a foundation that took in $18,800,000 and gave out to charity more money than it took in, $19,200,000. I won’t settle this case!... — Donald J. Trump (@realDonaldTrump) June 14, 2018

So, whatever went wrong it looks as if the Foundation ended up in profit. Trump had been trying to wind up the Foundation in 2016 but, because f the trial, it was still running in 2018 and so some pyments to deserving causes were dalayed for two years.

This is what Trump's lawyer said:

"Unfortunately, the NYAG sought to prevent dissolution for almost two years, thereby depriving those most in need of nearly $1.7m.

"Over the past decade, the foundation is proud to have distributed approximately $19m, including $8.25m of the president's personal money, to over 700 different charitable organisations with virtually zero expenses.

"The NYAG's inaccurate statement of this morning is a further attempt to politicize this matter."

Refs:

https://www.bbc.co.uk/news/world-us-canada-46611178

https://ag.ny.gov/press-release/2019/donald-j-trump-pays-court-ordered-2-million-illegally-using-trump-foundation