If you've received a protected Word, Excel, or PowerPoint document you will need the Adobe Experience Manager Forms Document Security Extension for Microsoft Office to open the file.
Adobe Experience Manager Forms Document Security Extension for Microsoft Office
Using Document Security Extension for Microsoft Office software, you can maintain the confidentiality of sensitive information by protecting critical files against unauthorized access at all times - from document creation through distribution, archiving, and destruction - regardless of how the files are distributed or where they are stored.
32-bit or 64-bit versions of Microsoft Windows 7 or Windows 10
Note: Document security extension for Microsoft Office is also expected to work on Microsoft Surface devices.
32-bit or 64-bit versions Microsoft Office 2010, 2013, or 2013 desktop applications installed as part of Office 365
1.3-GHz processor or higher
2GB of RAM
100 MB of available hard disk space