By default, Google Chrome does not allow you to log in and authenticate with Google while on Incognito Mode. More information can be found in this article from their official Developers website.
The solution offered by Google is quite simple and only requires a single change on your browser settings.
Access the Google Chrome Browser and enter the following URL:
And you're done! By doing that, you'll be able to log in to UserGuiding, even on Incognito Mode.