I realize this post is very old, but while searching here concerning this same problem, I found this, so hopefully I can add something that may be helpful to team.
I’m not sure internet connection is problem.
problem was revealed on my pc in this error:
Checking dependencies (excluding Mac, HTML5, Linux)…
Updating dependencies: 99% (18300/18406), 3295.5/3296.6 MiB | 0.28 MiB/s…
Failed to download ‘http://cdn.unrealengine.com/dependencies/2466157-4ecb0085873
048178dd6d2b8872eea79/81594c92fcec0b95d7d0b47ad36aef8d2605c8b8’: specified p
ath, file name, or both are too long. fully qualified file name must be less
than 260 characters, and directory name must be less than 248 characters. (
PathTooLongException)
Press any key to continue . . .
I downloaded file manually but had no idea where to put it.