Outlook VSTO plugin help

I already have a project which hooks send event and performs certain check. Now I have to enhance this addin to check for a valid license and then take the subsequent actions. I already have a webview2 control which I am using to load a login page for user to login and then check whether the license is valid or not. But I am facing issue in opening a login window in user form or a wpf window . Even I have failed to launch it as A custom task pane. A help will be greatly appreciated .