What web site are you trying to download the install files from?
What error message do you see when trying to download the install files?
Have you tried using a different web browser, and turning your firewall off for the download?
Please clarify your question. Do you mean....
a. That you already have some version of Premiere Elements on some computer operating system and you cannot import files into the Premiere Elements project or the Elements Organizer that comes with Premiere Elements
b. You are trying to download the tryout for Premiere Elements 12 (or a purchased online version 12) from Adobe, and you are getting download failures?
If "a", what version of Premiere Elements do you have and on what computer operating system is it running?
If this is the case, questions about your source media properties will be asked.
If "b", how far do you get in the download from Adobe process when the "cannot download" problem sets in?
Do you have the antivirus and firewall(s) disabled during such a download? Did you successfully install the Adobe Application Manager (.exe file)
before you run the main file (.7z)? If you have a 64 bit computer, are you working with 64 bit download files; and, if you have a 32 bit computer, are
you working with 32 bit download files.
Let us start here and then decide what next.