Hi Anita,
thanks for reaching out. The “problem” is that TYPO3 is usually hosted or managed by agencies, partners (or your internal IT). support@typo3.com will not be able to help you in this case, because it is an issue of your setup.
So you would need to better contact your hosting provider or your internal IT to ask why the domain might not be accessible. Could be there is just a typo in the URL at some point? Or maybe an access restriction is in place, so you may only open the URL if you’re in a VPN or with a specific SSO installation.
Sadly, nobody of us will be able to tell you that other than the person(s) maintaining your TYPO3 CMS installation. I hope you’ll get in touch with someone who can help inside your company.