git source code problem

I have connected my github account as first picture1. But I had met the problem as follow:
git clone --depth=1 -b 4.17 ~/UnrealEngine_4.17
Cloning into ‘/root/UnrealEngine_4.17’…
Username for ‘’: owenustc
Password for ‘’:
remote: Repository not found.
fatal: repository ‘’ not found

Could you help me to fix this problem. I don’t know why??. I have follow the guide of the web:

My github account have not any message from UnrealEngine, which is showed as picture 1. But I have connected github.