I made the mistake of buying the dlc on steam and not I can't get Oceania on matrix games. I tried buying it here as well but it does not allow me to.

I tried buying a it from matrix games as well, But it does not allow me as I allready own it on steam.

What is the purpose of linking my steam account?

I bought shadow empire on Matrix games. And then I bought Oceania on steam. Is there a way to get Oceania on Matrix games? I tried linking my account and can see it in my library but can't download it.