Hi,
You use the OnNodeClick event and close the popup with the following code:
procedure TForm1.TMSFMXTreeView1NodeClick(Sender: TObject;
ANode: TTMSFMXTreeViewVirtualNode);
begin
TMSFMXEditBtn1.Text := ANode.Text[0];
TMSFMXEditBtn1.Popup.IsOpen := False;
end;