How do I connect my Zoho Flow Custom Deluge Function? I keep getting error 57 (Unauthorized Access)

Question

I am working on a project that involves Zoho Flow. We created a custom function that should update the item stock and status based on the sales order. However, when I try to run it I get error 57 (Unauthorized Access). I've tried multiple things and it still doesn't work. The connection seems fine when I tested it but it still work run.

See code below:

string Update_stock_or_change_inactive_item(string salesOrderId, string organization)
{
output = "";
salesOrder = zoho.inventory.getRecordsByID("SalesOrders",organization,salesOrderId);
output = salesOrder + " ";
productDetails = ifnull(salesOrder.get("line_items"),"");
lineitems = productDetails.toJSONList();
for each  item in lineitems
{
    itemMap = item.toMap();
    productId = ifnull(itemMap.get("product_id"),"");
    productName = ifnull(itemMap.get("name"),"");
    quantity = ifnull(itemMap.get("quantity"),"0");
    product = zoho.inventory.getRecordsByID("Items",organization,productId);
    productMap = product.toMap();
    //get product stock
    availableStock = ifnull(productMap.get("actual_available_stock"),"0");
    availableStockForSale = ifnull(productMap.get("actual_available_for_sale_stock"),"0");
    status = ifnull(productMap.get("status"),"");
    output = output + status;
    //check and update stock
    if(availableStock < quantity || availableStockForSale < quantity)
    {
        //update item to ensure that it is in stock
        new_values = Map();
        new_values.put("actual_available_stock",quantity);
        new_values.put("actual_available_for_sale_stock",quantity);
        new_values.put("status","active");
        response = zoho.inventory.updateRecord("Items",organization,productId,new_values);
        output = output + productName + " - stock updated to " + quantity + ", ";
    }
    else if(status != "active")
    {
        new_values.put("status","active");
        output = output + productName + " - status updated to active, ";
    }
    else
    {
        output = output + productName + " stock not updated, ";
    }
}
return output;
}