I got this figured out. Go to your google account settings and click on security. Here is a direct link
https://myaccount.google.com/security
On that page you will see a box labeled "Signing in to Google"
Make sure you have 2-step verification ON. Then click where is says APP Password. It will have you sign in to your account again. Then, in the first box click on EMAIL. In the second box click OTHER and you can name it what you want. Then click GENERATE.
It will pop up a 16 digit one time password. Write this down. Then go back to your tool and use this password when entering your sign in credentials.
I would have uploaded pictures but I don't see a way to attach anything to this message. It should be pretty straight forward though. Just make sure you enter the right settings for the gmail imap account.
https://support.google.com/mail/answer/7126229?hl=en
Bob Powell