If you are unable to login to the Postman application using Google authentication and if you are receiving the message - "The browser you are trying to login doesn't secure your account" as per the screenshot below:
Unfortunately, you are running into a known issue that is currently being tracked on our GitHub page here. Subscribe to the thread for further updates and feel free to add your comment there as well.
Currently, we do have a workaround for the same - our team has released a feature that lets you log in to the Postman application via your browser. Click on the link "Try on a web browser" as shown in the below screenshot.
If you're still facing issues with login please refer to this article here or feel free to submit a ticket to our Support by navigating to the below link: