Check out example codes for "unity create folder only if not exists". It will help you in understanding the concepts better.

Code Example 1

using System.IO;
  //check if directory doesn't exit
 if(!Directory.Exists(directoryPath))
 {    
     //if it doesn't, create it
     Directory.CreateDirectory(directoryPath);
  }

Code Example 2

string path1 = @"C:\temp\";
string path2 = Path.Combine(path1, "temp1");

// Create directory temp1 if it doesn't exist
Directory.CreateDirectory(path2);

Learn ReactJs, React Native from akashmittal.com