How to return message not matched compare when excel compare return false ?

if (areIdentical == false)
return "Not Matched Compare"

public IActionResult ExportNormalizedRelation()
{

        var InputfilePath = System.IO.Path.Combine(GetFilesDownload, "DeliveryGenerationNormalTest_Input.xlsx");
        using (var stream = new FileStream(dbPath, FileMode.Create))
        {
            Request.Form.Files[0].CopyTo(stream);
            stream.Flush();
            stream.Close();
        }
        bool areIdentical = ex.CompareExcel(dbPath, InputfilePath, out rowCount, out error);
        if (areIdentical == true)
        {

            pathToCreate = Path.Combine(myValue2,Month,"file" + DateTime.Now.Ticks.ToString());
            
                Directory.CreateDirectory(pathToCreate);

                List<inputexcelnormaltest> inputexcellist = new List<inputexcelnormaltest>();
                inputexcellist = ex.ImportNormalTest(dbPath);
                List<string> tabs = new List<string>();
                var outputTemplatePath = System.IO.Path.Combine(GetFilesDownload, "DeliveryGeneration_Output.xlsx");
                List<inputexcelnormaltest> inputmodulelist = new List<inputexcelnormaltest>();
             
                  

                        foreach (var m in tabs)
                        {
                            inputmodulelist.Clear();
                            inputmodulelist = inputexcellist.Where(x => (x.TabName == m && x.FileName == f)).ToList();
                            var dtimport = DatatableConversion.ToDataTable(inputmodulelist);
                            DataTable dtexport = new DataTable();

                            dtexport = _deliveryService.LoadExcelToDataTableZipData(_connectionString, dtimport);

                            ex.Export(dtexport, m, exportPath);

                        }

                    


        }

        string zipPath = Path.Combine(myValue2,Month,"result" + DateTime.Now.Ticks.ToString() + ".zip");

        ZipFile.CreateFromDirectory(pathToCreate, zipPath);

        return PhysicalFile(zipPath, "application/zip", Path.GetFileName(zipPath));
   
    
   
}