Two processes. One to make the ISO creating process function (ISO creating tool I think) which you download first and then the actual download. These were specifically from MS.
Then the problems start. (though on another occasion it all worked faultlessly.)
It seems that calling down the OS ISO is a lot more difficult these days. MS, no doubt in a defensive mode against theft, now require the key for the machine it's going to be on. In my case, none of the OS keys from the iterations that had served me well for several years would work. In desperation, I applied the original sticker key from a machine I'd sold years ago, but it worked - that time. However, it's also a potential dead end because sometimes their computer tells you to go to the manufacturer for support. Yeh, right. HP and their bloat.
In this case, it was all to lay hands on a new copy of W10 that was upgradeable to 64bit, and what's more aggravating, the copy running the target machine was on an authenticated OS 10 that they had foist upon me. Mind you, I'd got the key for that via Belarc.