Hi,
I want to build the UnrealEngine 4.22 from source.
I followed these instructions: [Unreal Engine on GitHub][1]
I was able to connect my Unreal Account to my Git acount
The 404 happens for sure if you don’t have authorization.
Since it looks like you have it hooked up, I suggest giving it a few hours to see if resolves itself. If not consider disconnecting and reconnecting to your Github account.
The Major Point ist to go on Git, search for “EpicTeamAdmin” oder “EpicGames” in the user section and then there should be the message “You’ve been invited to join the Epic developers or something similar” just cliced it and it works