Haven’t filed taxes in 4-5 years

Hi everyone.

My ignorance on this subject was startling, but here I am.

I moved from the USA in 2018, paid taxes in 2019 and then again in 2020. I did not pay since then because I was informed that I did not have to pay taxes if I did not work in America. Imagine my shock when I found out this wasn't true.

I have permanent residence in the EU and work here and pay the taxes here. But what do I do about filing in the USA?

Thanks for your time.