Yes, that's the link.
I think I may have accidentally downloaded a system updater rather than an installer. I was having App Store problems. When I'd click on one of the links on the "How to get old versions" page, it wasn't properly firing up the App Store application. I realized that it was probably because I was clicking the link from Firefox rather than Safari. I switched Safari, but still didn't get to the right page in the App Store. Ended up having to reboot, and it finally found what appears to be the correct download. It's been downloading for the past couple of hours and is nearly complete. I'll find out shortly if it will install on the external disk without a previous OS on it. If not, I guess I'll have to find a disk copy app that will copy Sierra over from my internal drive. I have no idea whatever happened to my Sierra installer, but I seem to recall that it would only install over an earlier version of OSX. I'm keeping my fingers crossed, and will report back later.
BTW, I heard on another forum, that if you have an installer that is past its best before date, all you have to do is disconnect from the Internet and set your computer's date back a couple of years, and the installer will work just fine.
