The software you find on this page is absolutely free for use and with absolutely no warranty. I'm just happy if it's useful for you.
I do no longer work regularly on these apps. Once I switched from Apple's Objective-C to Swift when it came out. It just looked promising. But only as long as you could not look through Apple's mist they spread when announcing their Swift. Honestly, I love my MacBook. It's from 2010 and served me until 2019. But it was the last good product from Apple (don't get me started with that Touch Bar!). So, coming back to development, that Swift turned out to be just lame. They added language constructs over a couple of iterations that should have been there in V1. Now they are at V5 and each version felt like having to do a complete re-write of the source. Not funny. Anyway, before starting a lengthy rant here, I do hope my effort is not squandered.
Another PITA. Since OSX is getting more and more paranoid in the attempt to trump Vista you can no longer just open apps from the context menu. So, before attempting to run the app in a more recent OSX you need to gag it for a moment. Once you enter sudo softwareupdate --ignore "macOS Catalina" from the Terminal you are allowed to start the app. Additional you need to grant access to the calendar. Once the app is up you can revert the last setting with sudo softwareupdate --reset-ignored.
Funny enough that mechanism did not hook on one of my apps until a certain magic moment. After that I needed that gag all time.
P.S. Not sure about this issue still being present :-/ Probably you should first go without that rude method.