403 Forbidden

Hi team. One of my email addresses has been used by a member of my family and they accessed it using Microsoft Mail, which has now been discontinued. I'm trying to access the email address through My Virgin Media (Quick Link to Virgin Media Mail) but getting the 403 Forbidden message. Can someone please help me access the webmail so I can organise a new email client for my family member? Or perhaps there's another way to manage this email address?

Thanks