Want to use a view url from docusign to embed it in a iframe and allow somebody that is not the signer to review the envelope

I tried with the prefill tabs, but still, when the status is “sent” and I download the PDF as “combined” , still the fields are empty

This is how I set the values: 

templateRole.Tabs.PrefillTabs.TextTabs.Add(new Text
{
    TabLabel = fieldName,
    Value = fieldValue,
    Locked = "true",
});

Note: the pre-fill text tabs are already created in the template. I set the “data labels” with the same names that I pass to the “fieldName” argument.

this is how I download the Pdf : 
Stream combined = envelopesApi.GetDocument(accountId, envelopeId, "combined");

Can somebody help me? 

Thank you ​@Adrian Dev , 

I did it, and it did the trick! Thanks.

Still, I'm curious why the pre-fill tabs aren't working for me.

Follow these instructions from the DocuSign page : 

var apiClient = new ApiClient(basePath);
apiClient.Configuration.DefaultHeader.Add("Authorization", "Bearer " + accessToken);
EnvelopesApi envelopesApi = new EnvelopesApi(apiClient);
PrefillTabs prefillTabs = new PrefillTabs();
prefillTabs.TextTabs = new List<text>();
prefillTabs.TextTabs.Add(new Text { PageNumber = "1", DocumentId = "1", Value = "MyValue" });
Tabs tabs = new Tabs();
tabs.PrefillTabs = prefillTabs;
envelopesApi.CreateDocumentTabs(accountId, envelopeId, "1", tabs);

In my code I did create a Tab array object and I got this :

{
  "prefillTabs": {
    "checkboxTabs": [],
    "radioGroupTabs": [],
    "textTabs": [
      {
        "locked": "true",
        "tabLabel": "OfficeName",
        "value": "ABCDEF"
      },
      {
        "locked": "true",
        "tabLabel": "OfficePhone",
        "value": "999-2222"
      }
    ]
  }
}

// Set the prefill tabs for the envelope
envelopesApi.CreateDocumentTabs(this.account.AccountId, envelopeSummary.EnvelopeId, "1", config.GetPrefillTabs());

where, config.GetPrefillTabs() ; returns an list of Tab that contains the data above

The "OfficeName" and "OfficePhone" fields were previously created in the template using the pre-fill fields section.