Can't open Rhino6 trial for Mac

I have recently downloaded a trial version of Rhino 6 for mac to make sure the software will run on my older MacBook. I currently have Catalina 10.15.3 as the OS on my computer. When I go to launch the application, I get a window that is Verifying the application but won’t open. My computers is a 2012 MacBook Pro. 2.9 dual core Intel I7 processor and 8 GB memory.

that should work as long as catalina runs ok on that machine-

try deleting that install and download again/ reinstall. any luck?

It’s a DMG so it first Verifies the download, then mounts the Rhino 6 Volume.
At that point a dialog opens that prompts you to drag Rhino 6 into the Applications folder.
Do that.
Then you can 2-finger click on the Rhino 6 Volume and Eject it.
Use your LaunchPad to start Rhino 6.

Any luck?