Thanks for the info.
I have been unable to even determine what versions the latest supported by Sierra.
I now assume that 8.1 is the latest version for Sierra. It came installed in my machine, I think.
I do not want to upgrade my OS from Sierra, since many of my applications no longer run in upgrades. But Keynote keeps asking me to upgrade, then goes into a loop asking me to load an older compatible version. But downloads nothing. I will now stop trying.
I also have an M1 iMac running Monterey which runs keynote 13 and latest Topaz, but not my old Office or Adobe CS apps.
I go back and forth between machines to work.
I should mention that I am not commercial, so cannot justify the expense of needless software upgrades.
I just want what I have to work. Every so often I prefer to buy a new machine.