Using New Outlook on Windows for personal email, calendar, and contact management
Hello,
I also had the problem and digged in a bit deeper using sysinternals Process Monitor to see what exactly fails, when the system tries to download the file in the temporary outlook folder. There I figured out that my problem was a somehow missing Attachments folder!
Please press WIN-R and type %userprofile%\appdata\local\microsoft\olk and press Enter.
Then an explorer windows opens. Check if you can see an Attachments folder. If not create one and problem might be solved for you.