At the moment, I can’t download unreal engine 4.5.1 : it keeps telling me it’s resuming, but it does not download anything anymore. I’m using a yosemite macbook pro.
I tried removing everything UE related and re-install : even trying to download older releases does not work : the symptoms are the same : the launcher keeps re-stating it’s resuming download, but it’s not downloading anything.
I worked it out why it didn’t load. The macbook pro was migrated from an older macbook with unreal engine installed. After removing everything unreal engine related from the macbook pro ( I used this info : How do I uninstall UE4 on a Mac? - Installation & Setup - Unreal Engine Forums ) I was able to install UE4 again.