Vagrant provision and not finding /vagrant?

I am trying to provision a VM, using Vagrant and virtual-box, for development and I am unable to access the /vagrant folder where I had expected my base configuration files to be, to copy to their locations.

My directory structure is:

provision/
   install.sh
   config/
      nginx/mydomain
Vagrantfile

The contents of the Vagrantfile are as follows:

require 'yaml'
myproject_version = "0.22.1"

VAGRANTFILE_API_VERSION = "2"

Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|

  config.vm.box = "ubuntu/xenial64"

  config.vm.synced_folder ".", "/vagrant", create: true, group: "ubuntu", owner: "ubuntu"

  config.vm.provider :virtualbox do |vb, override|
    vb.name = 'myprojectserver-dev-standalone'

    # please customize hostname and private ip configuration if you needed.
    override.vm.hostname = "myhost"

    # frontend-webui
    override.vm.network :forwarded_port, guest: 5050, host: 5050
    # admin-webui
    override.vm.network :forwarded_port, guest: 8080, host: 8080
    # services
    override.vm.network :forwarded_port, guest: 8081, host: 8081

    override.vm.provision :shell do |s|
      s.path = "provision/install.sh"
      s.args = "/home/ubuntu ubuntu"
    end
  end

end

In my script I try:

ls -l /vagrant/
cp /vagrant/provision/config/nginx/mydomain

The problem is that the /vagrant directory doesn't exist. I tried creating it manually and then re-ruing the provision process, but no change.

Can anyone suggest what I may be doing wrong?