free Malwarebytes for MAC running MACOS Catalina 10.15.2?

Yes. Then unstall it (help menu) until you need it again as its 14-day trial has an RTProtection daemon running at the highest priority (-15) of any process on the Mac.

Is it a good idea to download and run free Malwarebytes for MAC running MACOS Catalina 10.15.2?"

It's a great item to use. Here are some links, directly from the developer. If you do want to uninstall, be sure to use the uninstaller.

Downloads:

1. Malwarebytes Anti-Malware for Mac
2. Malwarebytes Uninstaller

Yes a very good idea.

Other good ideas…

Effective defenses against malware and ot… - Apple Community

Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support