Help for Newbie

I need to reinstall Norton 360 on my laptop (sent in for repair and Norton Removed); I now have a "trial" subscription and am not able to reinstall with my Product Key that is good for two years, because it says I need a new subscription. 

Please help. I'm not sure if I need to uninstall the "trial" of Norton Securit of what...thanks for any assistance. 

*Forgot to add that I'm using Windows 10. This is so frustrating to not download what I already paid for!