hi I bought on Amazon what I thought was Microsoft Office Professional plus a few days ago, when it came it was a key, how do I use it, I saw the Picture I was convinced it was the whole thing, am I stuck with a key I can't use, forgive me I'm old, I only bought it because my pc keeps asking me to put an activation code in, when I open emails I purchased office pro plus 2019 from www.microsofthup.com which seemed legit but now im having 2nd thoughts. The link to download and install office worked fine but when I check my product key on Microsoft it says my product key is invalid. 4JIL.