If you are using 2-step password verification in Gmail- you need to generate the new password. After generating the password- follow all the steps described in this article.
To generate the new password follow these steps:
1. Connect to your Google account. Click on the top right corner and click "My account".
2. Click Security and App passwords
3. Enter the password of your Gmail account > continue.
4. Click Select app > select "Other (Custom name) > enter Teamgate and click > GENERATE
5. Copy your app password for your device (from the yellow field)