OK, I see what I did. I downloaded from the first download button I saw on the page you gave me which was for 11.0. I just now looked and found it for Catalina a little further down. Crossing my fingers.
it says it's for Catalina but after I downloaded it, I got a message saying this update needs macOS version 11.0. I don't know what to tell you.
This d/l on the MacUpdate page to which I linked is for Catalina.
I d/l'ed it, and it launched as expected in my 10.15.7.
