Hi @Carlos_Alberto,
In order to be able to manage your Yahoo! Mail using Microsoft Outlook, firts you need to enable the option to allow yourself to log in to Yahoo account from non-Yahoo apps and devices.
In short you will need to use app password instead of your regular password (app password can be generated under security page of your account). To do this, login to your yahoo account from web browser and click on your name (top right corner) and select menu Account info → security (scroll down to generate
app password)
Here you can see a nice tutorial (with more details) I followed and solved my issue.