Aangepaste code voorbeeld sebastiaan

        private void buttonShowLibaries_Click(object sender, EventArgs e)
        {
            // Configure credentials
            url = textBoxServer.Text;
            buttonUpload.Enabled = false;

            if (!url.Contains("https://"))
            {
                MessageBox.Show("Please enter a valid URL.");
                return;
            }

            string user = "admin@ThomasMoreStudent06.onmicrosoft.com";
            SecureString password = new SecureString();
            foreach (char c in "TMPassword06")
            {
                password.AppendChar(c);
            }

            // Connect to the sitecollection
            using (clientContext = new ClientContext(url))
            {
                // Load the lists
                clientContext.Credentials = new SharePointOnlineCredentials(user, password);


                ListCollection listCollection = clientContext.Web.Lists;
                clientContext.Load(listCollection, lists => lists.Include(
                        list => list.Title)
                    .Where(list => list.BaseType == BaseType.DocumentLibrary)
                );
                clientContext.ExecuteQuery();

                foreach (List l in listCollection)
                {
                    if (DoesUserHavePermissions(l.Title, PermissionKind.DeleteListItems))
                    {
                        listBoxLibraries.Items.Add(l.Title);
                    }
                }
            }
        }

        private bool DoesUserHavePermissions(string name, PermissionKind permmask)
        {
            try
            {
                List TargetList = clientContext.Web.Lists.GetByTitle(name);
                clientContext.Load(TargetList, T => T.EffectiveBasePermissions);
                clientContext.ExecuteQuery();
                return TargetList.EffectiveBasePermissions.Has(permmask);
            }
            catch
            {
                //log
                return false;
            }
        }