Federated identity management using Active Directory Federation Services
- Try to open the URL with Internet Explorer on the same machine. Does it work?
- Try to open the URL with PowerShell on the same machine (Invoke-WebRequest -Uri <URL>). Does it work?
If 1 is YES and 2 is NO, we just have a .Net TLS incompatibility issue. And you'll find the fix here: https://learn.microsoft.com/en-us/mem/configmgr/core/plan-design/security/enable-tls-1-2-client#bkmk_net (the SchUseStrongCrypto registry value).