The deploy process in Trellis assumes the server being deployed to is also managed by Trellis. Because of this I wouldn’t recommend using Trellis to deploy to a non-Trellis server.
You should consider using something like Capistrano instead. We have a production ready script that you can more easily tailor to your needs and there’s also a screencast you can buy for additional help: https://github.com/roots/bedrock-capistrano
For reference the Trellis commands are:
// Provision the server
ansible-playbook server.yml -e env=<environment>
// Deploy using the helper
./deploy.sh <environment> <site name>
// Deploy running the playbook directly
ansible-playbook deploy.yml -e "site=<site name> env=<environment>"
// Rollback the latest deployment
ansible-playbook rollback.yml -e "site=<site name> env=<environment>"
As you can see from this list, you attempted to provision the shared server, not make a deployment. Fortunately the SSH connection failed, preventing you from doing any damage. I’m sure your host would appreciate you using a disposable $5 Digital Ocean droplet with any further Trellis tests.