I can not download lasted version

When window asking for downloading new version appeared , I clicked on download to update my libre to latest version.
After that a window of safari pop up and showing that it was downloading, but it can not (never) finish downloading. I’ve already check the speed test on speediest.net. It give me 7.3 Mbps for download speed.

another question is when the window showing this information “The last time you opened LibreOffice, it unexpectedly quit while reopening windows. Do you want to try to reopen its windows again?” pop up, I can click neither “Don’t reopen” nor “reopen” So I can not use Libre anymore right now.

First thing I would try is to reset the user profile: For details please refer to: https://wiki.documentfoundation.org/UserProfile
This should solve the problem “Don’t re-open”, “Re-open”

From where do you download? I do it always from: http://www.libreoffice.org/ and then select the version I want.
How do you conclude that your download is not completed?
Can you download other files of the same size?

Updating LibO
When you download the next version of LibO you still have to start the installation process to update your current version.