I discovered today that I was running the game via an external hard drive instead of an ssd, so I re-installed the launcher locally, deleted the default cache folder and launched the launcher.
What is happening is, that every time the launcher tries to download the game starts at 2.5~ GB after a short time the progress bar goes back to 0, the download interrupts and the cycle begins again after a couple of minutes.
I uninstalled the game and reinstalled a couple of times, the issue persists.