Please double check the command : cd sandbox.repo /tmp. This will not work so if you are getting no such directory that is correct. Please point to the link you referred to resolve the problem.
The error here states that it cannot connect to the repository. If you are using the public repository then make sure you can connect to the link and no firewall is blocking your connection. If you are using the local repo, please check the firewall and if the user you are using to connect to the repository has sufficient privileges.
Hope this helps. If the comment helps you to find a solution or move forward, please accept it as a solution for other community members.