Seeing the three servers under Azure Arc > Machines confirms Arc onboarding, not that they completed Azure Local registration or are deployment-eligible.
On each node, verify a supported Azure Local release, then run Azure Local Arc initialization or Configurator as local administrator with the same tenant, subscription, resource group, and supported region selected in the wizard. Confirm required resource providers are registered and the deployment user has the documented Azure Connected Machine, Azure Stack HCI, Reader, Key Vault, and Storage permissions. Ensure Azure Policy and outbound firewall rules allow Arc extensions.
Refresh Add machines when registration completes. Eligible nodes appear as Ready or Not validated; the wizard then installs extensions and validates matching OS versions and symmetric network adapters. Nodes must not be domain-joined before deployment. If they remain absent, compare tenant, subscription, resource group, and region across registration and the wizard, then rerun registration after correcting any mismatch.