As I suspected, you have put the files together with Pirates of the Caribbean installation. Those files cannot be mixed because original New Horizons mod runs with Storm engine 2.0 (ENGINE.exe) in your folder. This is what you can do, download New Horizons for Maelstrom engine from this link
New Horizons by ChezJfrey (you have all the files there, then just copy/paste the files from your Maelstrom Engine that you bought on itch.io). Remember, the files that you need are: modules (folder), Config.exe, fmod.dll, Maelstrom.exe, Maelstrom.exe._lc. I prefer DirectX9 64 bit.