Go to redeem.microsoft.com/, sign in using your existing Microsoft account, or create a new one.
Enter your product key, click next. If you receive an error saying “Code not found. Try re-entering it. If that doesn’t work, contact the merchant.” – Please use the guide HERE
If the product is correct, select Confirm to finish the redemption process. Now you’re ready to install Office – See “Installing Office” steps below.
Go to the Microsoft Services & subscriptions page and sign in using your Microsoft account if you’re not signed in already. This is where you can see and manage all of your activated Office products linked to your Microsoft account, if you need to reinstall a program in the future you can do so from this page.
Select Install link next to your Office product.
Select the options you want with the “Other options” link (such as 64-bit and language), and then select Install. This will download the setup file to your PC/MAC ready for you to run.