He already paid the previous $5 million. Technically it's in an escrow pending appeal, so Carroll doesn't have it yet. But regardless, Trump is out $5 million.
Now Trump has four choices:
Pay the $83 million to Carroll
File an appeal, which means either paying $83 million into an escrow account or putting a lien on his properties and getting a bank to pay $83 million into an escrow account. Either way, Carroll gets the money as soon as she wins the appeal
Do nothing. This is the worst option, because after 30 days Carroll's lawyers would start choosing Trump properties to auction off and/or directly withdrawing money from his bank accounts.
Declare bankruptcy. This could introduce a delay, but it will inevitably result in Trump properties being auctioned off.