Hytale requires the server operator to own the game in order to run a server.
During your first launch, you may encounter a prompt to authenticate for the updater

Follow the URL to authenticate with your Hytale account, this will start the install/update process.
After the installation is complete and the boot up of the game server is complete the first time, it will prompt again for an authentication.

Type in to your console and authenticate again:
auth login device
Once your server is authenticated to the Hytale backend, you should be ready to go.
If your Hytale server is offline for too long, you may need to do the auth process again, but otherwise it should persist across restarts.