A new user may not be able to access the website for a few reasons: When the user was created, did the administrator set the user’s status as "Active"? If not, open that user's profile, check the Active option and then click Save. When the user was invited, did they...

This following documentation from Microsoft outlines IP’s and URL’s that should be whitelisted. Add IP addresses and URLs to allow list - Azure DevOps | Microsoft Docs In addition to what’s documented, whitelist the following IP’s: 52.186.101.40 168.62.52.104 The most...