Download Norton Internet Security and I cant add devices to other computers

Downloaded and bought a renewal subscription via my pre installed application. My subscription allows my to add up to 3 devices. I was able to download and received my Product Key but cannot use that same Product Key to download on other device.

I signed up using the same email. Logged in with the same email on another computer but able to download it.

Keep saying its already been used.

I need help, advice and a solution.