google drive v2 prompting sign in after publish

I have published a web application, developed by asp.net web form in my server windows server 2016-IIS. My google drive api is enabled and published. From my server it works but not from client. Now, whenever I test it from the client then the google user sign-in page prompt. I do not know what wrong I am doing or what else need to be done. Please review my code. Thanks

protected void Page_Load(object sender, EventArgs e)
        {
            GoogleConnect.ClientId = ".........";
            GoogleConnect.ClientSecret = "...........";
            GoogleConnect.RedirectUri = Request.Url.AbsoluteUri.Split('?')[0];
            GoogleConnect.API = EnumAPI.Drive;
            if (!string.IsNullOrEmpty(Request.QueryString["code"]))
            {
                string code = Request.QueryString["code"];
                string json = GoogleConnect.PostFile(code, (HttpPostedFile)Session["File"], Session["Description"].ToString());
                GoogleDriveFile file = (new JavaScriptSerializer()).Deserialize<GoogleDriveFile>(json);
                tblFileDetails.Visible = true;
                lblTitle.Text = file.Title;
                lblId.Text = file.Id;
                imgIcon.ImageUrl = file.IconLink;
                lblCreatedDate.Text = file.CreatedDate.ToString();
                lnkDownload.NavigateUrl = file.WebContentLink;
                if (!string.IsNullOrEmpty(file.ThumbnailLink))
                {
                    rowThumbnail.Visible = true;
                    imgThumbnail.ImageUrl = file.ThumbnailLink;
                }
            }
            if (Request.QueryString["error"] == "access_denied")
            {
                ClientScript.RegisterClientScriptBlock(this.GetType(), "alert", "alert('Access denied.')", true);
            }
        }
        protected void UploadFile(object sender, EventArgs e)
        {
            Session["File"] = FileUpload1.PostedFile;
            Session["Description"] = txtDescription.Text;
            GoogleConnect.Authorize("https://www.googleapis.com/auth/drive.file");
        }
        public class GoogleDriveFile
        {
            public string Id { get; set; }
            public string Title { get; set; }
            public string OriginalFilename { get; set; }
            public string ThumbnailLink { get; set; }
            public string IconLink { get; set; }
            public string WebContentLink { get; set; }
            public DateTime CreatedDate { get; set; }
            public DateTime ModifiedDate { get; set; }
        }