Error when Get files from specific URL SharePoint C#

I have problem with sharepoint when I try to get all file in a specific url.
I’ve try get files in url

https://mycompany.sharepoint.com/

It’s work, but when want to get files in url

https://mycompany.sharepoint.com/sites/Processing/Shared%20Documents/Forms/AllItems.aspx?viewid=b59c189a-26e1-42ff-b0b8-0e5aefc93734&id=%2Fsites%2FProcessing%2FShared%20Documents%2FGeneral%2FApp2020

It returns error Microsoft.SharePoint.Client.ServerException: File Not Found.

This is the first time I work with sharepoint. I’m look forward to receive your help. Many thanks.

Here is my code:

var targetSiteURL = new Uri("https://mycompany.sharepoint.com/sites/Processing/");
ClientContext cxt = new ClientContext(targetSiteURL.GetLeftPart(UriPartial.Authority));
cxt.Credentials = new SharePointOnlineCredentials(login, securePassword);
                    
var list = cxt.Web.GetList("/Shared%20Documents/Forms/AllItems.aspx?viewid=b59c189a-26e1-42ff-b0b8-0e5aefc93734&id=%2Fsites%2FProcessing%2FShared%20Documents%2FGeneral%2FApp2020");

var listItems = list.GetItems(new CamlQuery());
cxt.Load(listItems,
items => items.Include(
item => item.File));
cxt.ExecuteQuery();                    
this.lblMessage.Text = listItems.First().File.Name.ToString();

var list =cxt.Web.GetList("sites/Processing/Shared%20Documents")

File file = cxt.Web.GetFileByServerRelativeUrl("/sites/Processing/Shared%20Documents/test.doc");
cxt.Load(file);
cxt.ExecuteQuery(); 
Console.WriteLine(file.Name);
Console.ReadKey();