STEP 1 > install virtualBox
sudo apt install virtualbox
wget https://releases.hashicorp.com/vagrant/2.2.19/vagrant_2.2.19_x86_64.deb
sudo apt install ./vagrant_2.2.19_x86_64.deb
vagrant --version
mkdir vagrant_project
cd vagrant_project
vagrant init ubuntu/trusty64
vagrant up
vagrant ssh
All this started after I added these settings (in Vagrantfile):
config.ssh.username = "vagrant"
config.ssh.password = "vagrant"
config.ssh.keys_only = true
config.ssh.insert_key = true