This did not work for me. I tried both downloads on the page (https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solut...). Initially, Mac reported it as unsafe and wanted me to move it to the Trash, but I opened Security & Privacy and indicated I wanted to "Open Anyway" despite the risk. This brought up the installer. I responded to the prompts only for it to report "Installation failed" immediately. It reported "Configuration files were not found. Please make sure that Endpoint Security Installer was properly exported from the SmartEndpoint."
I tried this at least a half dozen times over the past month or so and esp. after Big Sur updates, just to see if OS fixes would help.
In retrospect, now that I've resolved the issue, in part due to the additional understanding I gained here, a big part of the trouble was being directed to a page that includes several downloads and no reassurance about which one is the one I ought install on my machine. One could go to the download page, choose the wrong one and think he had done what was instructed.
Now, in my case, I had attempted and installed several of the packages many times, including both the correct package and incorrect ones. However, when I did install the incorrect one (e.g. the one that fails immediately when you attempt an install) I was given to thinking it must be the correct one because it at least had a visible interface while the actual correct one has no visible interface.
That said, the root issue (the failure of the UI itself) was the primary culprit for the trouble I experienced. Even now that I can use the software I still can't access the UI at will. It tucks itself into the background and provides no affordances by which to expose it, though it will at times reveal itself, fortunately.