I did an amended tax return at the beginning of the month. Almost instantly it said it was accepted by both the federal and state. Was I supposed to mail anything in?

Just wondering since it's been over the 21 days since I filled. I remember it saying something about having to mail it in but the file it had me download didn't include the instructions like it said it would and when both got accepted I thought I was good. Just want to know if I need to mail something in or just keep waiting for my return.