You have downloaded the 32bit version, Apple dropped support for 32bit apps from Catalina onwards. Download the 64bit build, which I have running on my Macbook Air 2012 with Catalina. Perhaps it only became available in the last few hours :)
You'll get a popup on running saying that the app can't run because it can't be verified. It can, just open security in system preferences and hit open anyway. Only do this when you trust the source of the executable, obviously.