ACX Check Plugin won't install on Mac OS Catalina

I am a new user. I read that it was recommended to install the ACX Check plugin. When I try to install on my Mac OS Catalina it says there are no apps to open the document “acx-check-ny.” How do I get it to install? Am I trying to download the wrong plugin? Thank you.

I’m not a Mac user, but the instruction are [u]here[/u].