Office 2016 repeatedly asks for credentials opening documents

Office 2016 subscription repeatedly asks for login credentials when opening files from SharePoint.

Fix:

Create new registry key to force use of older authentication method.

run REGEDIT

navigate to the following key

HKCU | Software | Microsoft | Office | 16.00 | Common  right click on Identity then create new 32 bit DWord value Name this EnableADAL (case sensitive)

Exit registry, restart the PC then try re-opening a SharePoint Office document. You should be asked just once for your credentials, then they will be cached for future use.