Can't. download a programs because Microsoft Windows application are not supportive by MacOS

You can't install Windows only software on a Mac any more than you can install Mac only software in Windows. An app has to be written and compiled for both the hardware and OS it's intended for.

What are you trying to install?

If you want to run a Windows program you have to install Windows. Or, look for an similar Mac app that does the same thing.

What program are you talking about?

Do not install AVAST. Do not install any third party app that claims to protect, clean, boost performance, etc. The Mac OS has built in security.

Ugh! Not to mention Avast is the worst possible choice.

https://fortune.com/2020/02/12/free-antivirus-software-avast-selling-user-browsing-histories/

As in the old pirate prose, Avast ye all who enter here…