Yahoo Calendar - cant synchronize

I have sbcglobal.net email address, which is AT&T service provided by Yahoo. I'm able to successfully configure Yahoo mail account in iOS Mail, however using "Other" rather than predefined Yahoo mail. When I do that, iOS Mail synchronizes mail and notes, but not calendar or contacts. An attempt to specify CalDAV account as https://caldav.calendar.yahoo.com according to https://help.yahoo.com/kb/SLN4704.html fails. I tried both with the real Yahoo Mail password as well as with the application password I created in Yahoo account, and they both fail.

If I try to add Yahoo Mail account while selecting "Yahoo Mail" rather than "Other", I see another prompt of the webmail, which as I understand comes from AT&T after it sees my @sbcglobal.net address as opposed to @yahoo.com one, with the checkbox "keep me logged in for 2 weeks", and it always fails authentication - I also tried there both "real" password as well as application password, to no avail.