You can download Symantec Norton offline installers for Windows without a Norton account. You just need to choose one that works for your computer + product key:

• norton.com/latestns (Norton Security)
• norton.com/latestnsbu (Norton Security with Backup, aka, Norton Security Premium)
• norton.com/latestn360 (the discontinued Norton 360)
• norton.com/latestnis (Norton Internet Security)

You can copy norton.com/latestns and paste the above URL in the address bar and save the file directly to your computer. 

Before installing any Symantec Norton security product, you must totally uninstall any existing similar security product(s) and turn of Windows Defender before installation can proceed.