Convert System.IO to UnityEngine.Windows

I have never used UnityEngine.Windows and it seems it lacks a lot of functionality of System.IO. Can Anyone anyone explain how to convert from System.IO to UnityEngine.Windows? I’ve read a lot of threads on it but I think the way my save system is set up is making it difficult for me.

        string subDir = Path.Combine(Application.persistentDataPath, "Saves");
        string path = Path.Combine(subDir, curSaveSelected);
        if (!Directory.Exists(subDir))
        {
            Directory.CreateDirectory(Application.persistentDataPath + "/Saves");
        }
        foreach (string file in Directory.GetDirectories(subDir))
        {
            if (Path.GetFileNameWithoutExtension(file) != "Temp")
            {
           //Bunch of stuff not related

Like what is the equivalent of Path.Combine, or Directory.GetDirectories, as these are not present in UnityEngine.Windows.

I really appreciate any help,
Thanks.

Do you have using System.IO; in your code at the top? Both Path.Combine and Directory.GetDirectories work fine for me.