How to run BetaClock on Windows 10, or restore original Win10 Calendar app

I also like BetaClock. It ran fine on WinXP, yet it won’t minimise to the systray on my Windows 10 computer.

I can launch the BetaClock 517 program & get the calendar pop-up from the menu, yet it all disappears when I close the program window. Do you know of any remedy for this?

Alternately, is there any way to restore the original Win10 calendar app? I naively updated the Calendar app from the Microsoft Store, & it replaced the nice simple Calendar app with full-blown Outlook, a very unwanted & offensive thing for MS to do!