Unreal Engine 4.11 installation issue

I tried installing UE4.11, but after a whole night of downloading (my internet isn’t super-fast), it gives me this error -

Any idea what might be going wrong? And what the fix could be, other than trying to re-download everything afresh?

When download is finished, Windows is asking you some permissions. If you’re not there to answer, it fails after a while.

I don’t know any fix other than re-download and be there at the end.