Hey @14geronimo 
Welcome back to the Postman Community! 
You get that from a browser window, if the browser hasn’t opened up automatically you can use either of the unlined methods in the centre of your image, you either open in manually or copy and paste the URL into a browser.
Once you sign in through the browser window, by entering your details, it should redirect back to the desktop app. If it doesn’t, you can use select the authorization token option which will display your token.
This can then be used back in the desktop app to login.
