I have downloaded the 10 iso and tried to install it on my laptop running 8.1 Home Premium. The setup guide asks for the product key and does not give me the option to skip. When I input the key (determined by pcadvisor) it rejects it saying that key did not work.
What am I doing wrong?
How exactly did you "download the ISO"? And what version of Windows 10 is it?
That won't work if you don't upgrade first.
Downloaded from Microsoft.
Win10_N_English_x64.iso
I'm trying to upgrade Windows 8.1 Home
You downloaded the wrong version. You want Windows 10 Home without the N.
Where did you get that file? Did you rename the file? There ain't no N file.
You can upgrade to Home there:
Windows 10 Home: Upgrade or Purchase - Microsoft Store
Or download it there but you'll have to Mount the file instead of clean install:
Windows 10
There most certainly are N versions, both from Media Creation Tool and Microsoft Tech Bench:
Windows 10 ISO Download - Windows 10 blog