I got to download it from the Asset Store actually, Unity put it back for a little while afterwards. I think your best bet would be to ask directly customer service about it. That's what I did and they were able to tell me that the version was coming back to the asset store in about a month. Sadly they removed it now, since I believe it only works with 2018.3 or something. Good luck!
Viewing post in Book Of The Dead: Environment comments
Since I had previously "bought" it I was able to redownload from Unity and I hosted on mega here: https://mega.nz/file/COhkEBAI#YdL36fG6f2-619HhE90dV2QlGrFY1yZMc8KJ84-DQug