it's normal it cannot find this box if you haven't downloaded it yet.
I tried and it works perfect, it downloads and start the box, i share you my basic config (which is what i tested)
Vagrant.configure("2") do |config|
config.vm.box = "ubuntu/bionic64"
end
This is my output:
Bringing machine 'default' up with 'virtualbox' provider...
==> default: Box 'ubuntu/bionic64' could not be found. Attempting to find and install...
default: Box Provider: virtualbox
default: Box Version: >= 0
==> default: Loading metadata for box 'ubuntu/bionic64'
default: URL: https://vagrantcloud.com/ubuntu/bionic64
==> default: Adding box 'ubuntu/bionic64' (v20200304.0.0) for provider: virtualbox
default: Downloading: https://vagrantcloud.com/ubuntu/boxes/bionic64/versions/20200304.0.0/providers/virtualbox.box
==> default: Box download is resuming from prior download progress
default: Download redirected to host: cloud-images.ubuntu.com
==> default: Successfully added box 'ubuntu/bionic64' (v20200304.0.0) for 'virtualbox'!
==> default: Importing base box 'ubuntu/bionic64'...
==> default: Matching MAC address for NAT networking...
==> default: Checking if box 'ubuntu/bionic64' version '20200304.0.0' is up to date...
==> default: Setting the name of the VM: amos_default_1583767787636_71616
==> default: Clearing any previously set network interfaces...
==> default: Preparing network interfaces based on configuration...
default: Adapter 1: nat
==> default: Forwarding ports...
default: 22 (guest) => 2222 (host) (adapter 1)
==> default: Running 'pre-boot' VM customizations...
==> default: Booting VM...
==> default: Waiting for machine to boot. This may take a few minutes...
default: SSH address: 127.0.0.1:2222
default: SSH username: vagrant
default: SSH auth method: private key
default:
default: Vagrant insecure key detected. Vagrant will automatically replace
default: this with a newly generated keypair for better security.
default:
default: Inserting generated public key within guest...
default: Removing insecure key from the guest if it's present...
default: Key inserted! Disconnecting and reconnecting using new SSH key...
==> default: Machine booted and ready!
==> default: Checking for guest additions in VM...
default: The guest additions on this VM do not match the installed version of
default: VirtualBox! In most cases this is fine, but in rare cases it can
default: prevent things such as shared folders from working properly. If you see
default: shared folder errors, please make sure the guest additions within the
default: virtual machine match the version of VirtualBox you have installed on
default: your host and reload your VM.
default:
default: Guest Additions Version: 5.2.34
default: VirtualBox Version: 6.1
==> default: Mounting shared folders...
default: /vagrant => /home/amos
The only possible explanation is that you have bad internet connection...try to do a speed test here:
https://www.speedtest.net/
if you have bad connection try restart your modem or contact your internet provider