Loosing Malware

macOS includes anti-malware, integrated with macOS, and enabled by default:

macOS - Security - Apple

Safely open apps on your Mac - Apple Support

Apple Platform Security - Apple Support

Please skim this thread for a longer discussion about this:

How to check Mac for malware/virus, etc - Apple Community

I completely trust Apple's macOS to protect against malware. I have never used virus protection on any of my Macs since the 1st one in 1985. I have checked out and tried Malwarebytes free version just to see what it is, how it works, etc. I have never found anything on my drive with it. I do trust it and it is about the only malware this recommended by the experienced users on this forum.

The app Malware bytes is still useable on your Mac. The Apple message you read, but clearly did not understand, was informing you that when the new OS is released, the current version of Malwarebytes would not work. I assume that they are working to upgrade their app and it will be compliant by the time the next OS is released.

I too completely trust Apple's OS to be safe and secure from viruses. Time has proven this to be the case. No one should ever install any of the anti virus apps on the market. None of them solve any problems and will often cause major problems, and will certainly slow down the computer. I hope this helps you to feel more secure.