Have you purchased a copy of Office 365 previously? Although the apps that come with Microsoft Office 365 (i.e., Word, Excel, PowerPoint, and Outlook) are free to download from the Mac App Store, you may have to purchase Office in order to activate them before you're able to use them. I'm happy to help you sort this out so you can start using that app the way you expected to. If I'm understanding you right, you're being asking to verify your license when using the Office 365 app that you downloaded from the Mac App Store.
