What version of Unity/UnityHub/Etc do I need to run this thing under macOS 10.15 (Catalina)?

I selected individual/free, because I want to get a sense of what this whole Unity thing does, and downloaded UnityHub, expanded the dmg file and dragged it into /Applications. On opening the app I get the following error message, and wonder how to get this stuff working. (I’ve been running Catalina betas for a while.) Thanks!

“Unity Hub” can’t be opened because Apple cannot check it for malicious software.

This software needs to be updated. Contact the developer for more information.

Chrome downloaded this file today at 11:23 AM from store.unity.com.

I don’t own a Mac, but my guess is you follow Apple’s instructions at the bottom of the below page, which they just posted a couple weeks ago.