Cannot download 1099-DIV information from Vanguard Brokerage.

It could be due to many reasons. 

Have you tried to manually enter the information?  To enter Form 1099-DIV, here are the steps: 

In TurboTax online,

• Sign in to your TurboTax account and select Pick up where you left off
• At the right upper corner, in the search box, type in "1099div" and Enter
• Select Jump to 1099div
• Follow prompts

I have the same issue. Why should we have to enter the information manually? I purchase TurboTax Delux so I can upload the information automatically. Very disappointing.

Have you contacted Vanguard concerning the issue you are having downloading your documents?  They may be able to assist you with your issue.