Install a Snapshot 1.14.2 Pre-Release 3 server through the Control Panel (Servers → Select your server → Game servers → Add Game Server → Snapshot 1.14.2 Pre-Release 3)
I had trouble modding my server at first but support was a massive help with that and once we worked through the troubleshooting together and the server ran, we've been using it ever since and its been absolutely brilliant!!!