So, unlimited PTO is actually a financial hack. There are laws on the books that say if you earn your PTO via accrual, then it's legally compensation and if you leave without taking your PTO the company is required to pay you for those hours. So unlimited PTO allows them to say that PTO is not part of compensation and they don't have to pay you for any accrued vacation time you didn't take because there is no accrued vacation time.
In practice, it just means that you have to meet whatever expectations your boss puts on you, including if those are expectations are to not take PTO when you want, and if you take it anyway you'll end up getting canned for "insubordination"
