alexandro I don't know, just guessing. Maybe you were rate limited? Maybe try again with repo sync -j8
like they use in the instructions.
Also, looks like they know this kind of thing happens so they say just try again:
If your network is unreliable and repo sync
fails, you can run the repo sync
command again to continue from where it was interrupted. It handles connection failures robustly and you shouldn't start over from scratch.