老师为什么我的提示不是空仓库

The authenticity of host 'github.com (52.74.223.119)' can't be established.

因为这是私有的所以我换了一个权限为public的仓库，但是提示还是permission denied，这是为什么。。

fatal: Could not read from remote repository.

Please make sure you have the correct access rights

and the repository exists.