Offline licenses are typically available for (formerly VNC Enterprise) plans, especially the Enterprise tier.
You generated a key for RealVNC Enterprise 6.x, but you installed RealVNC Server 7.x. Fix: Uninstall the current server. Download the legacy version matching your license, or contact sales to upgrade your license to a newer version. realvnc offline license key new
Get Your Hands on a New RealVNC Offline License Key Offline licenses are typically available for (formerly VNC