The New York Times report on Trump's financial " issues" is quite informative.
He's personally responsible for $421 million in loans, one of which, for $100 million on Trump Tower, is interest only, and comes duein 2022 or 2023.
Basically, Trump is extremely " leveraged", and his golf courses/resorts have been - and continue to be - big money losers. As the article also mentioned, Trump has asked for loan payment postponements; if Trump is reelected, banks may be put in the awkward position of needing to sue a sitting president for loan repayment, judgements, and possibly foreclosure.
Also, Trump's tax write offs are questionable, and possibly illegal, especially the $71 million he received in federal tax reimbursement, which is the subject of a long running dispute with the IRS.
Anyway, please read the article.