To install Office 2016 for Mac, you must first visit Microsoft's site and log in with your Microsoft account. If you don't have one, you will need to create a Microsoft account here.
You can find the Microsoft website here.
After you have logged in, you can enter the product key you received from us, follow the instructions of the installation manager, and download the installation file.
Once the file is downloaded, double-click on the installation file to start the installation and follow the instructions.
If you have any questions, our customer service is available by phone at 0800 056 3102 or by e-mail at firstname.lastname@example.org.