Thank you very much, Matreya. I just ordered it. I didn’t expect it to be available anywhere other than the App store or an Apple store or from someone who already has it.
I’ve gone through the usual process to DL (several times) and made it to the hidden Sierra page and clicked the DL button. This is the first time I’ve had a problem with a DL from the app store. As noted above, what lands on my desktop are the images shown above, rather than a file with an installer.
The OS appears to be operating as it should. I DL all security updates when they are offered. There’s obviously something wrong with me or the Mac but I don’t know which it is.
Thanks again for your positive input.