How to convert byte[] to StringT?

In FDK development, I want to access registry to get information.

StringT GetDirInfoFromReg()
{
   HKEY hKey;      
    CharT       SubKeyName[]= "SOFTWARE\\airport raw data";      
     CharT      ValueName[] = "template"; 
  CharT keyValue[64];
  IntT i;
       
     BYTE        ValueData[64];      
     DWORD       Buffer; 
  StringT  key=NULL;
       
     //open key   
     if(RegOpenKeyEx(HKEY_LOCAL_MACHINE,SubKeyName,0,KEY_ALL_ACCESS,&hKey) !=ERROR_SUCCESS)      
     {      
         printf(      "Error:        Regedit        cannot        be        opened! ");      
     }      
     else      
     {      
     //read key value      
     Buffer=sizeof(ValueData);      
     if(RegQueryValueEx(hKey,ValueName,0,NULL,ValueData,&Buffer)==ERROR_SUCCESS)      
     {
          //Convert ValueDate  to StringT

    key=(StringT)ValueData//***************************Error:I can not get the right data.

     RegCloseKey(hKey);      
     }      
           
     }

  return key;

}

I don't know how to convert byte to StringT.