PLEASE HELP! ESTIMATED TAXES! URGENT!

Please - Can you advise me? I just (in Feb 2021) received a $10K penalty payment demand (payable next week) from NY State saying that I failed to pay estimated taxes in 2018 on the large capital gains from the sale of my home in mid-July of that year. I had no clue at all that I needed to pay estimated taxes in the same year that I sold, and instead had a tax preparer prep my 2018 taxes and sent huge tax checks to both IRS & NYS on the due-date Apr 15, 2019. Now that I received this demand letter (and have the ability to.protest it), I have researched and it seems(?) that I may NOT in fact owe this penalty because apparently the requirement to pay estimated taxes is based on your PRIOR-year tax liability. In my case, I was not working in 2017 (the year prior to my 2018 home sale), and had no income in 2017, and therefore did not have a tax filing requirement (and therefore I did not file in 2017), and had no 2017 tax liability.  I cant tell if I am understanding the rules & all I'm reading on this topic correctly and if in fact I can fight this giant demand for penalty payment. Can someone please advise me as I dont know if my understanding is correct & that in fact I did not have to pay estimated taxes in 2018 on my home sale, by virtue of the fact that I didn't have a filing requirement or any tax liability in 2017. Kindly advise as I am terrified. Thank you so much in advance.