I think the commenter's question was more about _how_ you did it :) (Thanks for answering questions here btw)
Did publishers just reach out to say "hey, pay this fee"? Or did they straight up start with lawsuits/C&D? Or did you reach out to them and say "hey I got this site, how much do I pay you to become licensed?"
So I went out and found licensing pro-actively. I wasn't contacted before in a formal way. But I know they (NMPA) did sent C&D letters to over 40 domains eventually.