To open and edit Office documents stored in your Sync account, directly on your computer, you’ll need to have the Sync desktop app installed, and Microsoft Office installed (editing requires an Office license). The Sync folder works just like any other folder on your computer, allowing you to open and edit your documents and files, using virtually any application installed on your computer, including Microsoft Word, Excel and Powerpoint. When you install Sync on your Windows or Mac computer, the Sync app will create a special Sync folder. Open and edit directly on your Windows or Mac desktop

See the using the Microsoft Office mobile apps for iOS and Android with Sync article for step-by-step instructions. All Sync customers can open and edit documents and files stored in Sync, directly from these apps (editing requires an Office 365 subscription). Microsoft provides a full suite of mobile apps for iPhone, iPad and Android devices, including Word, Excel and Powerpoint. If your files are larger you’ll need to edit with the Office desktop or Office mobile apps. The maximum file sizes supported for web-based editing are 50 MB for.

Note: Personal and Free Sync customers also have the Edit in Office option, but do not have the View in Office option. When you are finished editing, click Back to Sync from the Office 365 editor (located on the title bar at the top of the editor window), to save your edits back to Sync.From the preview screen, click View in Office or Edit in Office (editing requires an Office 365 license).Sync Pro Solo and Pro Teams customers can open and edit Office documents stored in Sync, using the Microsoft Office 365 online web-based editor. Open and edit from the Sync web panel with Office 365 Document preview preferences for Office.Open and edit directly on your Windows or Mac desktop.Open and edit from your phone or tablet.Open and edit from the Sync web panel with Office 365.Sync includes Microsoft Office and Office 365 integrations that make it easy to open and edit Office documents stored in your Sync account using the Office for mobile, web or desktop apps, and save those edits back to Sync. Microsoft Office for Sync getting started guide

How to sync office 365 docs