1. Before installing the new Office package, please uninstall all old Office versions from your computer. You can find and uninstall these in the settings under Apps. If necessary, download the Microsoft Tool for Simple Bug Fixes to make sure that all old Office versions are completely uninstalled. Here Microsoft gives a detailed guide on how to uninstall all old Office versions. This is especially important if you've used a Microsoft 365 before.
2. Go to Microsoft's website: https://setup.office.com
3. Create a new Microsoft account or sign in to your existing one
4. Enter the product key provided by us
5. Download and install Microsoft Office 2016 Professional Plus

If you have any further problems with the installation or activation, please write to us by simply using our contact form and sending a screenshot of the error message at the same time. We are happy to help you.