While I cannot help you with the problems with KDE Connect. You could also try using the My Phone/Link to Windows app from Microsoft, that has worked for me on Windows to receive/make calls, send/receive text messages and receive notifications on my windows pc.
KDE & Plasma users
KDE is an international technology team creating user-friendly free and open source software for desktop and portable computing. KDE's software runs on GNU/Linux, BSD and other operating systems, including Windows.
Doesn't Windows have a phone-connect feature? (note: I am not a Windows user nor do I play one on TV)
It does. It is a Microsoft product so mileage may vary but it is a thing that exists.
Yes, it does. I've decided I may have to investigate that, though I'm not yet sure if it will support concurrent connections from multiple PCs to one phone like KDE Connect does.
I'm not about to install Windows on any of my personal machines to find out, however. I'll have to wait until I get back to work tomorrow.
My understanding of these kinds of programs is that they work intimately with the OS they are written for. So trying to use the one for Linux on Windows may not work or will work poorly.
Good programs.
I haven't made a Google account for this device, so perhaps I need to do that and install the Play Store version
You can use Aurora store for this to avoid using a Google account