html
<div class="welcome-dashboard" ng-controller="GatedDataExportController as vm">
    ...
                <div class="form-group">
                    <label for="startDate">Start Date:</label>
                    <input type="date" id="startDate" ng-model="startDate">
                </div>
                <div class="form-group">
                    <label for="endDate">End Date:</label>
                    <input type="date" id="endDate" ng-model="endDate">
                </div>
                <button class="btn btn-primary" ng-click="exportData()">Export</button>
            ..
</div>

js
angular.module("umbraco").controller("GatedDataExportController", function ($scope, $http) {
    var vm = this;
    alert("hello world");
    $scope.exportData = function () {
        var startDate = $scope.startDate.toISOString();
        var endDate = $scope.endDate.toISOString();
        // Call backend API to trigger export
        $http.get("/umbraco/backoffice/Website/DataExport/GetGatedExport?from=" + startDate + "&to=" + endDate)
            .then(function (response) {
                console.log("Export successful");
            })
            .catch(function (error) {
                console.error("Export failed:", error);
            });
    };
});

cs
public IActionResult GetGatedExport(string from, string to)
    {
        // get dates ...

        using (var scope = scopeProvider.CreateScope(autoComplete: true))
        {
            var db = scope.Database;
            string strSProc = String.Format(";EXEC sp_gac_export @@gac_startDate='{0}', @@gac_endDate='{1}'", fromDate, toDate);

            var results = db.FetchMultiple<ExportRegistrations, ExportDownloads, ExportDownloadByRegistration, ExportDownloadByEmail>(strSProc);

            List<ExportRegistrations> exportRegistrations = results.Item1;
            //....

            if (exportRegistrations.Count > 0 || exportDownloads.Count > 0 || exportDownloadByRegistrations.Count > 0 || exportDownloadByEmails.Count > 0)
            {
                var workbook = new XLWorkbook();

                // Export Registrations
                if (exportRegistrations.Count > 0)
                {
                    var worksheet = workbook.Worksheets.Add("ExportRegistrations");
                    PopulateWorksheet(worksheet, exportRegistrations);
                }

                //...continued

                // Create a memory stream to save the workbook
                using (var stream = new MemoryStream())
                {
                     Console.WriteLine("using var stream");
         workbook.SaveAs(stream);
         var content = stream.ToArray();
             Console.WriteLine("return file");
                    return File(content, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "dataexport.xlsx");
                }
            }
            else
            {
                // If there are no records to export, return an empty file
                return File(new byte[0], "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "empty.xlsx");
            }
        }
    }