Thank you, MacUpdate, and, thank you, Fruux.
Here it is, late 2018, and I'm trying to extract myself from the caved-in "silo" of the Apple ecosystem in regards to calendar, contacts, and more that no longer "play well" with each other across multi-vintaged Apple OS/iOS products.
I really enjoy and use BusyMac products, which no longer worked effectively with a growing number of our resources/tooling due to new Apple security processes, including their implementation and the performance of two-factor authentication.
I appreciate Uncoy's info tidbit, along with others, so, finding this page as part of a Google search is a blessing!
In our DCC (Digital Content Creation) work and consultancy, I appreciate having parity across iOS, MacOS, Windows, Android, and Linux systems without relying on the Google interface and limitations.
While there are certainly a number of details to work out, including bringing in Thunderbird, at least Fruux, BusyMac, and other resources have some pretty awesomely lucid and workable Help available! Wow!
Thank you for keeping this page extant!