Yahoo and AOL require an app password to add the account to Outlook, even if you don't have their extra security features enabled.
From
https://www.slipstick.com/outlook/yahoo-aol-accounts-outlook/:
To generate an app password to use in place of your "real" password:
Log into your account security settings in Yahoo or AOL and click on Manage app passwords.
Select your app from the list and click Generate. (Choosing the app is to make it easier to delete (revoke) a specific password if you need to later. You can use the app password in any application.)
Copy the password and paste it into Outlook’s password dialog. If you type it in, don’t include the spaces, they just make the password easier to read.
To change the password in Outlook 2016 and newer, use the File > Account Settings > Server settings menu.
