Inside the virtual machine:
wget https://raw.githubusercontent.com/mitchellh/vagrant/master/keys/vagrant.pub -O .ssh/authorized_keys
chmod 700 .ssh
chmod 600 .ssh/authorized_keys
chown -R vagrant:vagrant .ssh
If your src/tictactoe/ folder is empty, also perform this
Exit the virtual machine and do
cd
pwd
Make sure pwd tells you are in /home/vagrant
rm -rf src
No reload the vagrant machine to apply changes.
vagrant reload
If no authentication error occurs, the working folder should be mapped correctly (Mac).
If this does not work, try
vagrant box remove package.box
vagrant box add package.box --name Default
If still no luck, talk to the teacher.